I personally like option 2 the best since it's the easiest, but that probably won't happen. I might shoot for option 1. Just to satisfy my curiosity, maybe I'll waste a little money on some ducting and try to rig something up.

Since the screws on the back of the fan that attached it to the housing of the microwave were exposed, I probably won't get jolted with juice. But maybe I'll try plugging it in again, and then toss a live ant or some other bug on it and see if it survives, lol.

I think I can shape a metal bracket, screw it onto the back of the fan (using the holes and screws where it was originally attached to the microwave), and then attach the bracket to the inside ceiling of the cabinet up against the exhaust hole.

Then affix a piece of ducting over the whole thing (for the "housing"). And on the outside/top of the cab, I'll have to cover the exhaust hole with screen or something so no one gets their fingers caught in the fan blade, lol.

I'll definitely post some pics if I do this, cause if nothing else, it should be a "unique" looking exhaust sytem.