I don't have any details at hand. Top Gun academy makes experienced pilots into Training Officers and giving them latest tactical doctrine to bring back to the operational squadron. Now including air-to-ground training too. They also teach the Air Intercept Controllers. And they give pre-deployment training, updating the crews with the latest threat intel.
The F-21s were retired a long time ago and actually they were USMC and not used for USN Top Gun at the time but for USMC BFM and advanced courses. The US Kfirs you might still see are owned by a company that provides threat simulation on contract, being the enemy on ACMI ranges or in naval exercises. The USN and USMC still operate the F-5 with their aggressor squadrons, they are used for BFM (basic fighter maneuvres) and Integrated and Advanced Training Phases exercises. Top Gun trains these instructors as well as providing the academics for the large-scale exercises. The agressors used for the Top Gun course are nowadays F/A-18A Hornets, the F-16Ns were phased out. They also used F-14s for a while. The non-delivered Pakistani F-16A/B were taken on, but a few years ago the USN was told to return them when the embargo was lifted. Pakistan did get second-hand F-16s, but the USN was reluctant to give up their F-16s, so I am not sure what happened. Anyway, Hornet is the principle aircraft now.
And yeah, there's lots of sites, I always wonder about the up-to-dateness though.