Yes the P101 should fit fine. It's a little tight, but mine goes right on.
I put about 500 rounds through mine, before I sent it off for sights, grip saftey ect. It did not need any of the mods, or new parts. I just like my 1911 a certain way. By the way mine was a mil-spec not a loaded model. So you will alreadey have Novack sights and a decent grip saftey.
Can't help you on the light question, since I haven't tried one. I've put about 2000 rounds through mine and I like it the way it is. As gener says, you can make it just like you want. That's one of the great things about 1911s!