How on earth is that completely skeletal zombie (Not Tarman, the one that rises out of the grave) even able to move?
The same way a headless one can move. This random irregularity is a large reason why the Return films are generally regarded as worse than the ____ Of The Dead films by Romero.
The first one is well-loved among zombie fans, it's the sequels that are considered either disappointing or outright awful.
George Romero has nothing to do in any way with the Return of the Living Dead series. They were made by someone else entirely exploiting the fact that Night of the Living Dead was public domain.
To be fair that someone was co-writer of the original NOTLD John Russo, who yes since ROTLD has produced a lot of god-awful cash-ins but back then had the sense to hire Tobe Hooper, and when he dropped out agreed to replacement Dan O'Bannon's request to let him rewrite it to make it more distinct.
How are the skeletal zombies even able to move? For that matter, is there even any bit of a brain left for the Trioxin gas to affect?
And how is it that zombies without lips (Tarman, Lady Torso Zombie) are able to to make "M," "B" and "P" sounds when they speak?
Also, in the fourth film, why did they make a "minimum security area" for zombies?
Because the endorphins, adrenaline, and other "feel-good" chemicals that the brains produce would probably be overflowing in the brains of horny and drugged-out teenagers. The zombies are in constant pain from rotting, and only human grey matter can ease their suffering. If you were in constant pain, wouldn't you want the best pain-killers that you could get your hands on? Not only that, they're so easy to obtain!
Exactly how is it that rotting zombie teeth can bite clean through a person's skull?
Because it's a zombie movie. It is a zombie movie that is glorying in being a deliberately cheesy, exaggerated, trope-laden zombie movie. It's not in any way trying to be logical, realistic, or anything else, and frankly some of us are pretty grateful for that.
So Freddy has broken out of the chapel and making his way to the embalming room. Spider and Burt decide the best course of action is to make a break for it? They were armed with fairly effective weapons and Freddy was blinded by Ernie with the nitric acid, why didn't they just go find him, bludgeon him until his head was destroyed and then toss his headless body out the embalming room door? It was the safest room in the mortuary. Or why didn't they just break his limbs so he was nothing more than an immobile stump?
Because their overriding, overwhelming, all-consuming thought is "I want to get the hell out of here!", not "Time to kick some zombie ass!"
Why didn't the paramedics come back as zombies? After watching Return of the Living Dead on Chiller, I noticed that at least one of the attacked cops come back but the the paramedics just stayed dead.
Maybe they were just picked over too thoroughly? Maybe it takes longer for some people to come back?
You know the "they were just picked over too thoroughly" theory makes sense. After all the brain of the paramedic right next to the paramedic truck was seen being eaten by a couple of zombies in different scenes(like the send more paramedics one). Though it does make me wonder why they didn't pick the cops thoroughly now.