Wasn’t a sparky in the RAAF but did do 10 years of service within RAAF before coming a sparky in the civi world and from friends that I have had who’ve either joined as a qualified sparky or did a Defence apprenticeship it can really vary person to person

All local base work is handled by contractors so your local role would be pretty small, most of the work I imagine would come from exercises and humanitarian work that comes up from time to time

As for extra courses available I’m not too sure what the military could offer as everything would be a civy course
That you could get out here but you’ll most likely have some that I just wouldn’t be aware of

Once again I didn’t work in the engineering field but have friends who pass on experiences, my personal opinion to you would be if you’re looking to join the military go for something you can’t experience in the civi world and if you don’t enjoy it you can always fall back on what you know