My conclusion is: Do 1 and 2 this time but postpone 3, 4 and 5. Change the curve to a linear one, keep a single pool, see how things go. It's not good to suddenly change too many things. Sure we need more incentive for holding SP, but I don't like to add too much at once.

//Update: I need to make it clear that I meant to keep curation rewards for both root posts and replies.