1. Customizable interface would be a better idea (being able to move pieces around to suite your needs) I think the interface is nice and clean looking and easy to navigate, don't fix what ain't broken!
2. - 4. Depending on the body type you choose these stats change. I find playing with only the original body gets boring, so no need for them to edit it.
The current game will most like not change, interface for the new game will be new and snazzy and health and movement speed might also be edited then for a body similar to original.
Lastly try not to double post, just edit your original post.