So far, on the test server, here's what I've found:
- 5 building licenses, 290 soccerballs, limit 1
- 4x friary (creates 4 times as much beer), 840 soccerballs, limit 5
Everything else is a decorative item (flowerbeds in the colors of flags, 60 soccerballs)
I can also report that the Veteran General appears to be available for 4999 gems, limit 2! The permanent slot additions are 2990 gems each, limit 3.
It appears you get soccerballs through adventures that are purchasable (and probably come from quests, too) starting at level 26. The text on the repurchasable adventures calls them "replays" and says you'll get XP but no soccerballs.