On the first point I would agree that you should try a SP indirect fire class with 0 movement. Also, what happens if you give a mortar front, side, and rear armor? I did this in one of my OOBs for a mortar pit, but never tested it out. I get the feeling Andy has said before that this creates issues in game.
On the second point, I was thinking about doing this myself for my aircraft pack at a point, but figure I'll just post it here.
This link mentions a so-called "Hunter 80" program that gave Swiss F.58/A Hunters an AGM-65B capability. Might be interesting to put that in.