Hooking up the DC computer fans is a piece of cake.

Just take an old cell phone charger or something similar that has the AC/DC converter built into it. Cut off the adapter on the end, connect the two wires for your fan to it, and its done.

I converted a full size stand-up freezer. The mini-fridge shouldn't be too difficult. Not sure how easy that upper freezer portion is to remove though.

You should probably start by having the freon evacuated though. Not entirely necessary, but it does make one less thing to worry about and allows you to totally gut it out.

Nice pick up, let us know how it turns out!