Welcome Swithun - If you liked "The Stranger", you'll probably love "The Lady From Shanghai" and "Touch Of Evil". If you thought "Kane" was great, then check out "The Magnificent Ambersons" and "Chimes At Midnight". If you enjoyed "Chimes At Midnight", then check out Welles' other two Shakespeare adaptations "Othello" and "Macbeth". If you've enjoyed all of those, you'll probably be ready for some of Welles' more esoteric work such as "The Trial", "The Immortal Story", "F For Fake" and "Mr. Arkadin" (although you should probably wait for the Criterion Collection DVD set coming out next year which will present the best versions available of that title). Oh yeah, if you haven't seen "The Third Man", you've got to check that one out - although Welles didn't direct it, it's one of the best films he was ever associated with.
As far as books are concerned, you'll probably get a lot of differing opinions around here. Most agree that "This Is Orson Welles", a book based on actual conversations with the man, is good.