[MB.]

I agree with the majority of your suggestions, except I wouldn't be a fan of using challenges to determine eliminations (because then the Crystal Coxes of the world wouldn't stand a chance, not that they even get cast in the first place these days) and I think tribe switches and idols work in moderation, i.e. one idol at each starting tribe and one switch at the final 12. I would also add:

1) Jeff is fired and replaced with Abi-Maria Gomes
2) Chaos reigns however she sees fit