So far, I've got everything assembled the way I want it, and am making progress on it, albeit at a snail's pace (like everything else). Following are some photos of a pair of auto-defenses included in the Planetstrike sets.
Imperial Auto-defense weapons
To me, the auto-defense lascannons don't look like they can reach out and touch someone at 96 inches. To this end, I lengthened the barrel with some Evergreen plastic tubing and other bits.
The cannon targets an enemy flyer
The paint scheme is easy, just prime gray, pick out a detail or two and get some wash in the recesses. I think it serves the purpose.