yea...it certainly is a valid question. no-one's born with knowledge. we learn as we go along. so..never be afraid to ask..even at the expense of sounding a bit silly.
I figured that bioware used the same setup as in ME1, but apparently i'm wrong.
From the comments and the video, it's apparently safe to assume that they did make seperate costumes and body models
and now the texmod stuff is already happening. ME2 modding is looking really good right now.
Even more scary: