Patrick, I think this thread got lost a bit in the shuffle. Sorry for the delayed response, but I'll try to answer some of your questions here.
The MAC platforms are pretty nasty for the Covenant player. They can't move but I believe they can rotate, and with their range they work well as area-denial weapons.
The Covenant CPV is a brawler, but it is definitely made for knife-fighting range. It's plasma beam only has a 12" range, and it has no plasma lance option. Pair it up with some SDV corvettes, though, and it can really dish out heavy volleys of torpedos. I think it works best in the Ambush scenario where you can use it in your flanking battle groups.
I don't have the DSC support ships, so I can't help you there. I do have ADPs, Halberds, and Valiants on order though. Looking forward to mixing the ADPs and Halberds into my fleets.
Again I'm very sorry for the delayed response to your post, I've been off the forums quite a bit this summer with Real Life Stuff. I hope this helps and I hope you are continuing to play the game even with Spartan closing its doors. Feel free to post here any time about Halo, it's a game I really enjoy!