HI...just wondering how to restore a save from a couple of days ago. I've located the saves in user>Library>Application Support>Basilisk>BookIISaved Games and there is a folder there for each slot. What to do next? It appears that only the most recent save is available...can that be true?

You can save in different slots in the game, but if you always choose to save in the same slot (like Quick Save), then it gets overwritten each time. To keep backup saves in particular places, you have to save them in different slots.

You load them from those slots within the game itself.