re: Disposal is leaking under the sink. Never changed one before, any recs?

I've replaced disposals and it is nothing complicated or difficult. But from what you've described, it sounds like the leak could be at the bottom of your sink, where the drain attaches to the hole in the basin. If that's the case, it's an unusual place for a leak. The disposal drain, the part that you see from the top, should have a putty ring between the metal and the basin, and the thing should be tightened down by a threaded connection. Maybe reset the disposal, if that is the location of the leak. If it is anything internal, go get yourself another disposal and change it out.