Burning-Jay does Tekken 8 Models, but they are Patreon Exclusive. There is some from StickLove and Otegine as well that are Free to Use.
I haven't seen anyone port to XPS, but have seen MMD. I can't remember the user unfortunately.
Hi there! It really just depends on the person. Personally I don't know if I can do it, but it;s just a lot of research on people who can. Try looking into people who have done stage mods!