If the other people aren't providing a value commensurate with their compensation, you should fire them whether you have an expensive replacement on tap or not. If they are providing such a value, it's probably better to keep them in place. Too often people overestimate new hires and underestimate the value of institutional knowledge. But if you have people that need to be fired anyway, that'd be a good opportunity to do it.

If your bosses think you're an idiot, you should leave. If you ask the board for more money and they have more money to give, they'll probably give it, unless they think you're an idiot, and then you should quit.

If there's no way you can get the additional allocation, just tell the candidate that you'll hire him at 55k for now if he's still interested and give him a bump when the money for a raise materializes.

If you're upfront with people, life is much easier, and you'll find yourself looking over your shoulder much less. :)