I think it would be awesome to add p2p insentive by adding new things other then heroes like you have been. seeing as how you have new things like base backgrounds and pets maybe you could have some awesome pets or base backgrounds that you get exclusively by how much gems you have spent in total.
I agree. I think would be nice if CC updated their gifts for purchases made. It's a nice way to thank your customer base, who at least at one time, made significant purchases.
I don't think we need another hero. Dealing with the headache of yet another OP or pointless hero is something we don't really need right now. However, non-game impacting gifts would be very welcome.
Decorations, skins, backgrounds, things like that.