Transformation Control - I would suggest keeping it out of the NAS attachment slot area. Either of the currently discussed: corner of the BigItem graphic, or pop-up menu from a right-click on the Big Item graphic.

3) Knowing what you are transforming. Clicking, or a menu popping up from the BigImage gives a clear indication to the player as to what they are modifying.

Yeah, my projects already have different graphics for most weapons with their stock folded/deployed, and the ARS Magnifier System (ie. "proof-of-concept" for the utility of variable power scopes under NCTH) have their magnification factor set in both Interface and BigItem graphics.