My five cents right now. Do not spend time on IAP, it is not widely supported yet.
priority2: leaderboard "tagname" somehow, currently I can only request one leaderboard at the time, and then populate it, then request a new, but then I cannot use On Leaderboard loaded, since that is already true from the first request. so I have to turn off the first population events, and use a wait function to wait for the new data, then populate it.. works, but not nice, and causes delays. (i want both global highscore and friend highscore to be visable, maybe also the contextual.)
the other stuff, not needed as I see it.
I agree with paala s suggestion with chooseAsync and updateAsync