Right, the forking problem doesn't affect rewards. I had been staking on a fork a couple days ago before I decided to go offline until the fix was released. Since the fix was released earlier today, those rewards have been rolled back and replaced by new rewards from a block I staked today. So no problem at all. Even transactions should get rolled back with no loss (Please avoid doing this though.)

Staking with a small balance is not going to help the network much. So don't feel like you have an obligation :) It's true it would be nice to stake a block every now and then to earn interest, but again, with so few coins the odds are pretty small. I wouldn't worry about this aspect of things until you've built up a balance :)