I have brakes. I use them, and only them, for stopping.

My drivetrain is pretty compact - 39/15 fg.

I can pull it very tight, but then it seems like it binds a little. At least it doesn't spin as freely.

If I have it so it spins freely, with just a little slack, I can get it to come off if I press against one side by the chainring, but what would actually make it come of while riding?

Will too tight of a chain do damage to my hubs or bottom bracket?