1.In my opinion, season four up to six were far superior to the first three seasons. Even though the scoobies might have been slightly more likeable in the first three, the depth of the highschool years was much less than the one found in the eps in later seasons.
Before s4, Buffy was to me just a typical show about a bunch of kids fighting monsters, it wasn't until Spike joined the cast that the show got really really good.
On top of that, Spike getting chipped is probably the best plot choice the writers ever made. Without it, Spike wouldn't have been half the character he eventually became. Both fic and show wise I'll always prefer chipped and post-chipped Spike to the earlier version.
2.I can't stand Willow. I think she's annoying, that Alyson Hannigan is a highly limited actress and that the show would have been better off if Joss hadn't had such a crush on her. In fact, I think the show might have been better of with the actress who originally played Willow in the pilot. At least her voice would have been less annoying.
3.I do not believe that Xander was ever physically abused by his parents. He was most likely a victim of neglect and emotional abuse, but I don't think his father beat him on a regular basis, like fanon would like to have you believe.
4.I do think that Spike raped and killed children prior to being chipped. I believe that he was evil and that he was capable of enjoying torture, long as it didn't last too long. Any dislike of torture would not have been based in a dislike of hurting people, but in a lack of interest and a tendency to get bored rather quickly. I could see him start to torture someone, lose interest and then either kill the victim or leave them behind to starve to death, simply because his attention span wouldn't last long enough to have him finish it to the end. (not unless Drusilla or Angelus were involved and he wanted to do something for them, or to impress them)