I have used some gold to buy a hero in "Heroes of the Storm". Will that hero remain after the final game is released or will all the money disappear? Please cite your source if you answer the question.
After this announcement the 10th of July 2014 there shouldn't be any more wipes as far as gold and XP go.
... Also, there are no more planned wipes, so any XP and gold you earn from this point on will remain in your account for good... source
With the transition from alpha to beta there weren't any wipes. Neither from closed beta to open beta.
It'll be very strange for Blizzard to wipe all purchased content. Especially content that you can only purchase during the beta phase (certain mounts).