All these movies are old, probably 80th era.

1. Film about the girl who lives in mansion (or castle), probably in vampiric or Dracula's castle. I remember only one scene: somebody gives her a glass of water, but when she looks at it the water turns to blood and worms swmimming in it.
At the end of the film she kind of turns to a vampire (i can mistake) and crawl in the dirt.

2. Film about the man who travels with the robot in outer space. They both get to some planet, where they find a group of scientists. During the film they fight with some alien creatutes. In the middle of the film robot explodes, but main hero reconstruct him. Remember one episode: alien creature move into female scientist's body, after that others operate her on surgical table. During the operation the creature rips out of woman's body.

3. Thriller about some guy who make horror films, and killed other who didn't like his films, but with original method:
get small toy car with detonator under victims' cars and explode.

4. Some horror about the maniac who lives in theatre (or cinema). Inside theatre he uses ventilation tubes to move to any point of theatre and kill victims (mainly girls) during intermission (can be wrong). At the end of the film ventilation tubes become maniac's crypt, where he collect his victims.

Heh, I'll take the easy one... The Dead Pool

http://www.imdb.com/title/tt0094963/

#4 sounds like the hero and terror (good movie btw)
http://www.imdb.com/title/tt0095296/
hope that helps and if I am wrong oops at least it's a start

2 sound like something I'd wanna see

2 may be Galaxy of Terror.
4 may be Theatre of Blood or a Phantom of the Opera.
Years (when they were made or when you watched them would be helpful)