How the heck does the curse work? No mechanism is ever really suggested, and it appears to have New Powers as the Plot Demands. Horror is well and good, but when you get the feeling that the director is personally forcing the story into Screw the Rules, I Have Plot! it rather diminishes any urge to keep watching.
More importantly, WHY does the curse work? "Oh no, I was horrifically murdered by my husband, now I want to kill random, innocent people!" WTF?! What does that have to do with her murder AT ALL?! All the spirits involved in the Ju-On are all Jerkasses, and if I was consigned to die from the curse, I'd call their asses out on it first.
The implication is that the curse is mutating as it adds more ghosts to it's rally. As for why; Kayako's mother had her swallow literal concentrated evil as a Sealed Evil in a Can dealie. Everyone the curse kills, therefore, is sort of possessed by this all-consuming rage. It's not like they're of their own will or anything.
Also this is how Onryo actually worked in the old stories. The only difference between Kayako and a traditional Onryo is that in the old Japanese myths the ghost of a woman who was wronged by her husband would attack everyone except for her husband, while Takeo was Kayako's first victim.
Can someone explain me the whole scene with the "not sake" bottle?
In the second straight to video film, Kyoko, the realtor's clairvoyant sister, explains that psychic energy can be contained in alcoholic beverages. Essentially, the sake tastes bad to anyone who is susceptible to Kayako's attacks.
Would the curse be broken if someone re-killed Kayako, say by burning her, or shooting her repeatedly with a large caliber weapon, or killed her son/husband for that matter?
Eh, no. She's a ghost. She can't die again. This isn't Supernatural where you kill Ghosts by torching their bodies.
How in the world did the curse enroll a dead boy in school?