The clan perks for donation troops refund, while my clan hasn't reached that level yet, I could only assume is elixir refund but only for a certain percentage. Do correct me if I'm wrong. Besides, that's only applicable for clan war donations. My suggestion for rewarding donors include both donations made in clan wars and for donating to normal requests outside of clan wars, and not with elixir refunds but with small amounts of gold. I know, it's kind of a long shot.
As for the heroes being made available for clan wars even when upgrading, I searched the stickys for a mention of this but couldn't find it. Maybe I didn't search hard enough but if you could or if you remember, pls do enlighten me on SC's reply regarding this issue.
http://forum.supercell.net/showthrea...24#post3858724
Thanks a lot!