My mind wasn't fully engaged last night when I wrote my last reply. There was thread about Brimstone some time back and I now remember getting some info from our TACOPS folks on the system. Brimstone uses it's own seeker for radar acquisition, the rail assembly has a logic module that does the processing. I would still assume the need for a display and for the pilot to have some input into target selection but that's beyond my knowledge. Otherwise the missile rail will do the prioritization of targets, not the missile itself. In the simplest of terms, the Brimstone is using the missile seeker for radar acquisition, the missile "pod" is the processor that seperates the wheat from the chaff and prioritizes targets.
The Hellfire II gets a target handover a number of ways. At a minimum it gets a north east and down (NED) . It also has INS so when it is selected to be active it receives it's current location. From this, it can determine it's trajectory for optimal target identification and terminal flight. In addition, the missile will adjust it's trajectory and radar mode depending upon whether or not the target is moving or stationary. It can launch with it's radar locked onto the target prior to launch (LOBL) or it will launch with it's seeker off until it gets to a point in space (LOAL). It will also be given a second target, in case it can't lock onto it's primary target, which can be turned off with a button push. Distance to the target will also affect the flight path the missile will take.
The missile will get it's NED from either the radar, RFI (it tracks emitters), the TADS, stored targets or from electronic mail targets. Whether or not it knows "what" the target is is dependent upon what provided the target data. It may know it's a tank for instance if the handover was from radar/RFI, but if it was TADS or stored targets it just knows it's a target. The aircraft can prioritize over 1000 target but will only display the top 256 threats which is coincident to the number of hellfires an entire company could carry. This is where priority fire zones come into play, zones are created in the battle area by one aircraft and it will assign individual zones to individual aircraft. Now each aircraft can prioritize only the tragets in it's zone and will not fire into another zone. You don't have to use PF zones, it's just another tool. You can likewise create no fire zones in which the aircraft will consider targets in that zone a safety constraint preventing the missile from engaging targets in that area.
As I said earlier, RF missiles are great when you are fighting against a huge enemy force full of vehicles and the like and you are in a weapons free area (everything on the ground is a target). Otherwise they aren't usefull for much at all. Laser missiles are a different story, they are extremely precise and are the only type you are going to be able to use for CAS.
Finally when considering CAS from my experience, the ability to service really comes down to what your platforms/weapons danger close ranges are. It's all well and good that you can put ordenance on the ground but when troops call for CAS it's because the enemy has them by the belt so to speak and you need to be able to deliver very close to friendlies with confidence and accuracy.