looks cool. when I get home tomorrow I'll put it on my list to check out.
I foresee only a couple problems:
A. Mission editor needs to insert the unit names of all triggerable addon units.
B. in cadet mode, tracers will be visible
C. In multiplayer, sound and visual effects will be on the placing machine only.
D. The mines are directional, but the activation is not.
If it helps, take a look at what we did with claymores over at forum.thechainofcommand.net in the public downloads section. The scripts in the .pbo might give you some ideas.