Tokens for joining I think are still ok, it's pretty much the same as bounty campaigns. Despite the fact that some people won't use it, it still spreads the word. Giving tokens for confirming friends is however a little too much.
It's some sort of referrals bounty? For a start is ok I guess and you're right, some people won't use it but you rather register into a platform with 250,000 users or on a platform with 1,000 users ?
You get tokens for downloading the app so abusers will use their different google accounts to download the app without actually using it.