If getting professional testers is an option, I really don't want to see Early Access, especially for this kind of game.
Longer answer to the bonus question, I'm sure it's been brought up before one way or another: "Unlock the Kickstarter Backer EXCLUSIVE in-game item/skin/power/area", I'm really not a fan of that, especially if at higher tiers. It makes me feel as though I have to pledge at that tier otherwise I miss out on that part of the game (no matter how minor) forever. An alternative I like is "Backers receive early access (but not the Steam kind) to finished future update items/skins/powers/areas" assuming there are future updates.
I didn't read past the first page of this thread (sorry), but I really liked the "demo of the first level minus the dialogue and cutscenes/story" idea. I like seeing free demos, getting (ugh) "early access, but again, not the steam kind" to one of those for Kickstarter backers would be wonderful.
PS: Agreed with the Original Post about no "backer-designed" or "likeness in-game" or any of that as well.
(Apologies if any of this had already been discussed or something. Just stumbled across this thread after changing my e-mail preferences. Best wishes to everyone here, I'm super excited for this game!)
EDIT: After posting this, realized it's a bit of a necro... Sorry about that. Hope it's one of those rare "helpful/discussion-provoking necros", but if not, feel free to delete.