So, my question is... how can learn both 1) how to sail, navigate, operate, repair, provision, etc. (to a level sufficient enough to do it on my own) and 2) if I'll even like the live aboard/cruising lifestyle enough to make the downsides worth it?
I think wind_magic overstates things a good bit. Don't stress.
For sailing, about the best you can do is find someone else who needs racing crew. You will learn more that way than any other.
Navigation can be learned at USCG Auxiliary classes or books or on-line courses like Starpath offers.
Operation comes with the territory.
Repair skills (as opposed to resources) can come easily from pitching in as the race boat you crew on prepares for the season and needs help getting in the water.
Provisioning is easiest. People eat everywhere in the world. Keep an open mind and you can always eat.
The longest passages I can think of are in the South Pacific and rarely exceed a month. The longest hop I took crossing the Atlantic was three weeks. You can practice at home -- think about what you want to eat for a week and buy all the food at once (refrigerator is allowed -- most although not all cruisers do have refrigeration) and eat from that. Push to two weeks and do it again. You'll find it isn't hard at all.