Re: AC/DC circuit breakers?
 

You probably ought to still use a fuse in the circuit, I've seen smoke caused by relatively small batteries!

Re: AC/DC circuit breakers?
 

What size?

on the topic of circuit breakers:
Generally speaking, should you buy a breaker rated for the current the system is rated for, or that trips at or before that current? (trip amps vs. rated amps)

Re: AC/DC circuit breakers?
 

Breakers or fuses are usually sized to the wiring (at least they are in power distribution systems used in houses, cars, and FRC robots).

But you also don't want it to pop at any normal working loads.

As I said earlier, 18 gage wire and 10 amp fuse/breaker should be fine for your application.