BBD - despite what LM says
1. The cannon does not need to be 30mm or above - whether it's a 20, 25, 27 or 30mm weapon it'll still be handy. This has been demonstrated on numerous occasions in Afghanistan and Iraq respectively since OEF and OIF began. There's little evidence to suggest that troops in contact have responded to a strafing run by moaning that the gun being used isn't big enough.
2. You do not require an all PGM suite for modern CAS. Again, there is much evidence from theatre where unguided ordnance has been successfully employed in CAS - both bombs and rockets (CRV7).
3. US rockets can be fitted with a form of laser guidance, but they do not all have it as you might infer from LM's post. I'm not sure whether the capability has reached the front line yet, or whether testing is still ongoing.
100-series Hawk would probably be adequate for some tasks, but remember that it would almost certainly need to carry two fuel tanks underwing, leaving it with three pylons for weapons. You could have either the gun or a designator pod, but not both, and the weapons that could be carried on the outboard wing pylons would be limited compared to the range that could be carried on, say, a GR7.