Do I have to stay until payout or it doesn't matter?
You will be rewarded in all blocks found in the 5Nd after you stop mining ... ... ...
There is an exception. If you drop to dust you don't get it.
Dust is lower then .0001 but that is my tired old'head telling me to type this so I could be wrong.
All amounts are rewarded, the payouts are only (automatically) sent for non dust and people who have a payout address.