Yes, every item that you can carry is needed at some point in order to win. There is one immovable item that, now that I think of it serves no useful purpose, that is the mirror in the
hall. It's just there for fun (and because it was there in the real house)
Yes, Version 2.0 and higher has a background picture and an original musical score that can be turned on and off. It also features a choice of 4 different fonts to play in. Read the
Readme (in the installiation folder) and/or useable commands list (on this site) to find out how to toggle these features.
Yes, there are two different ways to destroy your chance of winning. so be careful and save often. One is a major puzzle in the game and if you think logically and reasonably, losing
this way can be avoided. The other is more of a joke to trying something really silly, so save if you're goofing around.
In either case, although it should be obvious there's no going back, the game does not tell you if you have made a terminal move, so save often.