I've owned handguns for 45 years and have never had a problem with ammo going stale or magazine springs losing their strength. I believe that quality ammo will last for decades if stored in a dry, dark place.
I do like to shoot and try to rotate my ammo, using up the oldest first. So I probably am not testing the limits of ammo in my particular case. And I agree with those who said that you should practice somewhat regularly with your gun to maintain proficiency. This would make your ammo questions moot.
As for the type of gun - revolvers are conceptually simpler than semiautos if you aren't going to spend much time with your gun.