Yes, you get Enterprise User access to FA if you host a feeder.
As of the beginning of the year, about 20% of military craft were ADS-B equipped. No fighter or bomber aircraft or UAVs had ADS-B (Out) as of 1/1/20, but 1,129 helicopters, 923 mobility aircraft, 259 C2/ISR aircraft, and 625 trainers had it. However, FA doesn’t offer tracking capabilities according to this: https://flightaware.com/about/faq#military.
With that said, I’ve seen users report C17’s, C5 Galaxies, C130’s, and other training aircraft showing up in their tracking. The Air Force says about 60% of military craft will have ADS-B (out) by 2025, so I don’t know if that means we’ll start seeing a broader selection of aircraft. From what I’ve read, fighter craft will be among the last to get ADS-B given logistical and technical issues outfitting these types of planes with new equipment versus a massive tanker. I doubt however that FA will report these by aircraft type - probably will be reduced to position-only and you won’t know the exact type.
I’m not aware of any configurable alerts that go by aircraft type only from FA. Maybe someone has figured out a way to customize your feeder software for this, but I’m not aware of a particular solution right now.