Others with more experience will chip in, but very simplistically, powder coating means:
stripping everything down to bare metal, degreasing it, etc, spraying an electrically charged coloured powder to the bare metal and then baking each piece so that the powder melts, flows and creates a very hard, durable, almost plastic-like coating. To my knowledge it can't be done on a spot basis - it's all or nothin'
I don't own a Foba stand (sigh), but if it works fine, I'd consider just having a good body shop (or self) remove the rusted areas & bubbles, feathering them (create smooth gradient from bare metal back to good paint) and just touching-up the areas with a close-match paint.
It's akin to comparing a full strip to the shell and restoration of a classic car vs. touching-up some rough spots on a valued, already paid-for ride.
That said, if in a dry studio, just a nice job removing the rust and bubbles might just be fine. Would create an interesting look - think brassing on an old Leica ;>
