Acually You can edit the foward movement and the players looking position, Ive done it. There are a couple other things that have been done too like throwing greneades, crouching, and meleeing. I was going to continue researching but my 360 broke.
They only release a litte at a time because that gets the community more excited about the dev mods. If they releasded it all at once it woulnd be as exciting.