For the limit switch circuit Jazz proposes, you should add a diode across the relay coil to suppress the inductive spike, which would otherwise reduce the lifetime of the switches. If you're using them just as limits, not home switches, then that's not the end of the world. Either way I'd be more keen on using a transistor in place of that relay, since it also (for all intense and purposes) removes the small delay caused by the relay contacts moving. Again, not such a big deal for limit switches but it would reduce the accuracy if these are used for homing.

I wouldn't bother fusing the fan - do you really care if it blows up, it's only a fan...