I don't have all that much time to go into it now, since I have to get ready for my second job of the day (bleh). However, putting Gambit in the movies would be a huge mistake.
First, there's really no point to his character in the movies. Wolverine took over the sort of roguish aspect that Gambit held in the comics. Iceman took over the relationship aspect. Also, his comraderie with Rogue as a fellow loner is gone as well, since Rogue can touch other mutants via movie canon. The only role that's left for him to play is as a face man... which isn't bad, to be sure. The X-Men as of X2 lack one severely.
However, secondly is the fact that Gambit is supposed to be dominating in any scene he's in. Welcome to the world of high Charisma. That won't translate well to screen at all, IMO. Hell, I wasn't fond of it in the comics either, but that's just me. In the movies I feel that unless he's the focus of the movie (bad idea, given above) he's simply detract from the movie in whatever scenes he's in.
There's a bit more, but I do have to get ready, bus to catch in fifteen.