The genetics of this film make no sense. Why is it that at the end of Seed, to make it clear to the audience that Tiffany has possessed Jennifer Tilly, does her eyes turn green? Human Tiffany has brown eyes and Human Jennifer Tilly has brown eyes. The Tiffany dolls has green eyes. Why are her eyes still green? Same goes with Chucky, Glen and Glenda. Why do Glen and Glenda have red hair and blue eyes when the genetics of the doll should have Charles Lee Rays human DNA (who had neither). We know the doll becomes human and takes on the genetics of the person whose soul inhabits it (in Bride, the police sheriff mentions finding Ray's fingerprints at the scene of crime). So why are the dolls painted on looks somehow being kept and even passed down on a genetic level?
The tv series answers a bit of this: Tiffany is shown to be the natural red-head, so that explains why Doll!Glen has redhair.
How do the dolls manage to package and mail themselves? Even Glen, who has lived his entire life in a cage, manages to get all the way to a Hollywood film studio.
In Curse of Chucky we see that (human) Chucky was obsessed with Sarah and possibly in love with her. But according to Bride Of Chucky, Chucky left a ring on Tiffany's mantle the night he was shot. The same night the scene with Sarah took place. So was Chucky in a relationship with Tiffany while he was obsessing over Sarah?
Chucky's relationship with Tiffany may have been mostly one sided. He makes it clear in Bride that the ring was in no way intended as a proposal. Instead, he hoped that she would sell the ring and make a profit from it since it was highly valuable. Also, he never mentioned her or tried to contact her in subsequent years. She's basically a serial killer fangirl, as seen when the guy she's with at the beginning of the movie is pretending to be a murderer to impress her.
The series is clearly elaborating on this, which as we now know Tiffany was in Chicago with Chucky when he had Sarah kidnapped. She also called the cops for Norris to have trailed him there. The flashbacks have yet to tie the ring back in, but that may come up in later seasons.
How does a doll (which weighs maybe 10 pounds max) manage to overpower an adult? (or even a kid for that matter)
Through surprise. The dolls never really face off against their victims. They rarely ever attack head on. They usually use the element of surprise for the majority of their victims throughout the films. On the odd chance when they do attack head on with a victim that is aware of them being alive and prepared to fight them, it's usually the climax, where the dolls often die. Child's Play 2's climax is a good example.
I assumed it was something he got from learning voodoo. It just increases his strength relative to his old body size.
The novelization for Child's Play 2 makes note that Chucky is stronger than he looks, and as John Bishop stated in this movie that the more time Chucky spends in a doll's body, the more human he becomes.
The tv series also confirms that Chucky is stronger than he appears, which he attributes to the power of Damballa.
What would've happened to Andy's soul had Chucky succeeded in stealing his body? Would he have effectively died and gone to heaven (as Chucky implied in 2 near the film's climax), or spent the rest of his life trapped in the doll's body instead of Chucky?
Both possibly. Once the spell was complete, if Andy did not die and was trapped in the doll's body, Chucky (in Andy's body) would have just killed him. Can't have a talking doll running around to people asking for help.
That is, assuming Chucky knew that the heart was the doll's weak point.
If Nica's fate in 'Cult' and the TV show is any indication, his soul would have stayed in his body, a prisoner with no control while Chucky gleefully runs around in it.
How does Tiffany know so much about Voodoo in Seed Of Chucky yet had to read "Voodoo For Dummie" in Bride of Chucky? It doesn't seem like Chucky ever taught her anything while she was a human and she struggled to bring him back to life. Yet a few years later, she is inducing magical pregnancies, spouting knowledge about said pregnancies, and using voodoo to split souls apart. Did she gain more knowledge while in Hell or something?
Simple. As you said, a few years have passed. She finished the Voodoo for Dummies book and moved on to some more advanced texts.
In hindsight, Tiffany doesn't really know anything about voodoo. She needs the Voodoo For Dummies book to bring Chucky back, but she only knows a voodoo pregnancy is excellerated because she experienced it herself. While it is a popular fan theory, there is nothing to indicate that Glen has two souls and that Tiffany split them between two bodies. From the movie, she just transferred his soul into that of the male child.
Related to the question above, what the hell happened with Glen/Glenda? Did Tiffany split his soul into each of the children (one evil, one good) or did she just transfer him into the boy's body and Glenda just naturally takes after her father? It seems to be implied she did the first when she says "We have a son and a daughter. Maybe we don't have to choose." But the film doesn't seem to offer any evidence either way.
While we aren't going to see Glen and Glenda until the Season 2 of Chucky, so far we know Chucky has clearly found a way to make multiple copies of his soul, and apparently did so with Tiffany too. This may in fact be explained in a flashback that involves how Tiffany did that with Glen and Glenda.
Maybe I'm just remembering it wrong but wasn't the guy Chucky blows up with the oven like his partner in crime? Where was he in Curse of Chucky? On a similar note, Curse implies that Chucky was fleeing his house after he was ratted out but I believe they say something else in the first movie.
Yes, it was his partner, Eddie. He is dead in Child's Play 1. He wasn't in Curse because it was over a decade after he was killed. Curse of Chucky seems to have retconned what events occurred the night Chucky died. According to Tiffany, Chucky was with her before he left and got shot down. According to Chucky, he had kidnapped Nica's mother and was with her when the cops showed up. Eddie...is just thrown in there somewhere.
Is there any real reason he couldn't have possibly done all three? He could have started off with Tiffany, got mad and went to kidnap Nica's mother. She called the cops on him to retreat, he called Eddie for help but Eddie had second thoughts and abandoned him, which is where the first film starts.
Chucky Season 1 has elaborated more on this. Chucky was with Tiffany in Chicago on that night but they had a fight. Which matches up with what Tiffany said in Bride. (The ring hasn't been mentioned though). He went to where he had Sarah stashed. However we now know Tiffany called in to rat on Chucky, which is how Mike Norris found him. Eddie's involvement here is still a mystery. Flashbacks did establish how Chucky met Eddie, so Mancini clearly hasn't forgotten him. It does feel like maybe Chucky just accidentally bumped into Eddie that night and Eddie chose to save his own tail than help Chucky. But then again maybe there's more flashbacks with Eddie and Sarah still to come.
In Bride Of Chucky, Jade opens Charles Lee Ray's coffin to find a rat infested grave. How could a swarm of rats be alive underneath six feet of dirt for over a decade?
While for movie reasons it's not shown, but in real life, the rats would probably dig a tunnel underground came into the plot, chewed through the casket and into the body. Of course many real life cemeteries do line their plots to help prevent that (Moles sometimes dig through cemeteries as well) but I suppose a serial killer buried in New Jersey might be an exception.
Here's an interesting one that hasn't been posted: you're the toy company who created the Good Guy dolls. Your doll becomes associated with a serial killer an urban legend, not exactly the wholesome and fun image your company was going for when you first made it. Why the hell do you keep manufacturing the doll for decades?
Not really decades. It's implied Chucky did some major damage to their image in the first two movies, and they temporarily retired the line as a result. 3 starts with them believing enough time has past for them to relaunch the Good Guys. It clearly doesn't work, since by the time of Bride the line is dead for good.
So, from what I understand, the in-universe official story is that Andy, Karen, Kyle, or possibly all of them are the ones who really killed all of the people Chucky killed (at least in the first 3 films), but were presumably declare not guilty due to insanity or the like. The problem is, this whole "official story" has some pretty huge plot holes, namely (and this is just going by the first movie as I haven't seen 2 and 3 in ages and none of the original cast (other than Chucky of course) comes back until the end of Curse). A. How would Andy know who Eddie Kaputo was, let alone where he lived? B. How would either Andy or Karen kill John as Andy was locked up at the time while Karen was with Norris at time. C. How would Andy (who is 6 at the time) understand how the shock machine worked, let alone use it to kill Dr. Ardmore?
Because even with the holes, it still makes more sense than a doll coming to life and killing people.
Why do most people don't believe that Chucky is alive or that he did mean things??
This is another one of those "on the other side of the screen, it looks so easy" scenarios. If you put yourself in the shoes of an average person in the world of the franchise, and look at the situation from a perspective of someone who hasn't encountered Chucky before, would you honestly believe him to be alive unless you saw it with your own eyes? It's easy for the audience to know, we watched the films and the TV series. But from the point of view of someone who has encountered Chucky for the first time wouldn't believe a plastic doll would be harmful, let alone hosting the body of a psycho serial killer.
While killer collectible toys are rare, you should know people do report all kinds of strange things and supernatural things to this very day. But there's whole groups of people ready to decry them as delusional superstitious rubes. I'd imagine these same people would do the same to people claiming a doll is alive committing murders.