you can use a low poly model as a wrap deformer on a high poly model but you dont need to. You can rig the high poly model if you want to. I'm not big into character animation so someone should be able to give you better advice about that. As far as clothes goes do you mean cloth? you can have the cloth on the high and / or the low but it depends on whether or not your machine can handle it. Again someone with more experience e.g. Kurt or Mike can probably help you more than me

Alan