is it just an installer or something?

It's a compressed installer to be precise. Usually crackers only put up the patch files, which is pretty useless for anybody wanting to pirate a game. Fitgirl repackages (and compresses) the game files together with the crack patches into a cracked installer, hence "repack".

And if you imported the game into steam for example can you be “banned” or VAT (idr the term)

Nope, though it will look funny in your Steam Status there is nothing to worry about. After all for all Valve knows you could be using a renamed version of a legitimate App, for non-steam entries in steam only the .exe name is known, nothing else.

Just a word of warning: be careful when torrenting the games, while Valve will not ban you for using them game publishers are known to sue when catching you torrenting them (usually the upload part in the torrent is what gets people but the downloading is not 100% safe either). You should definitely look into how to safely torrent stuff before committing to it in order to avoid any nasty cease-and-desist letters flying in your door.