1) I’m at 12,000+ rds, and have replaced recoil springs twice (every 5k), most recently with a LTT 12.5# spring. I concur that a trigger return spring is a good idea to have on hand. I haven’t broken one yet, but have preventatively replaced them in other 92s when removing them for other work.
2) I clean and lube mine every 500-700 rounds. It’s never been even close to “too dirty to run well”, but it makes me feel better.
3) I reload most of my practice and match ammo. On recommendations of others here, I tried .356 and .357 Gallant coated bullets in 147 gr. In back-to back testing at 25 yds, my groups were consistently slightly better with .356, so that’s what I’ve used for the last 18 months or so. YMMV.