As a former AAC ABFAC I can offer some light on the subject.
1. The reason the TACP FAC is a Commisioned Officer is because he commands a team of four or five personnel and will operate in remote area's more often than not. They are also responsible for abvising the Brigade staff on FAC and CAS matters. It sounds better coming from a Rodney! I recall that due to a shortage of Army Officers to fill the posts, the establishment were looking at allowing AAC WO's do the job, if they had previously done the job of an ABFAC.
2. Any AAC pilot who attends the FAC course will be CR'd when he achieves the requesite number of strikes ( hits preferably!) regardless of being an aircraft commander or not. He will however have to fly with a qualified aircraft commander to satisfy the crew composition. I was that man on many occasions. With hindsight it was alot of resposibility for a Cpl!
3. With reference to Longbow drivers becoming ABFAC's I can't see any problem with that, but I also reckon that the Longbow will be called upon to provide CAS rather than call for it!