I've been sourcing parts for a PMA and from what I've read those numbers are pretty spot on. Any higher than 15 volts is electronic ignition burn-up territory, although most seem to be rated more than that.
I can't comment on the size of the fuse, but remember the circuit is what draws amperage. Too high voltage damages components, too low, they don't work. Too low amperage damages the power supply, too high is irrelevant because the circuit controls amp draw. A fuse is like a canary, if it blows, you need to diagnose a problem, so if you're burning up batteries it's time to look elsewhere in the circuit.