No, it has no gain limit.

TPMTC can't exchanged for PMTC. They should be used for make bets is order to get a better position on airdrop ranking and get more PMTC (and BTC, at this moment only for two first places) on launch day. You can check how much PMTC will get checking rankings page.

Next weekend we will open our documentation pages, explaining how it works the system. But as I think, it's so easy to urderstand when you use the webwallet for some days.