Water change frequency

Well as far as too much, I would never go past a 50% of your tank volume. And the only time I would do a 50% is if something was very wrong with the water, like it was a tank crashing threat on my hands. That's just me though, some people like to throw in a 50% water change after 6 months or so. My normal water change routine for 92 is 10 gal every week with a 20 gal thrown in every 4 or 5 weeks.

As far as a 10 gal change every other day, that's sounds fine and IMO its a reasonable way to get the nitrates down. But since you're already at 80-100 ppm of nitrate, I would probably do something like a 20-25 gal water change, then switch to 10-15 gal everyday for about 2-3 days, then switch to 10 every other day. Definitely stay on track on nitrate tests to make sure it's coming down cause 80-100 ppm is pretty high.

If you do the 10 every other day, that might be too slow in getting the nitrates down. If it were my tank, I would want the trates lower sooner since there's fish in there already.

Btw are there corals in there?

Yes, because your Nitrates are already so high I would do a major WC first--about 25-30%. Then another aboyt a week later.

You have a corner filter== Wet/Dry?? Wet/Drys are major Nitrate makers. You may have to get a Nitrate reactor to get way down.