I'm running mine on Windows 7 on Bootcamp, and it's an older Mac, but I rarely get crashes.
I do have a ton of The Sims 3 folders, I keep them separate - basically I have one folder for each world I play. (Plus one for testing, and one that has the entire Store installed for when I need missing stencils.)
For me what causes these unexpected crashes are things like going in and out of CAS a lot, or doing a lot of things in a row (what I like to call "rampant mouse clicking"), especially when I'm building and I'm impatiently placing a ton of items without waiting for the game to catch up... Like you I've tried to make sense of crash logs, but generally it just tells me there was a 'catastrophic failure' of some sort, which is not helpful.
If you crash on loadup, though, it could be that something got corrupted. A factory reset may help.
I generally make a new The Sims 3 folder, put in my Mods folder, the options.ini from my old game, and a small text file called FeaturedItems to to stop the game generating that irritating FeaturedItems folder.
And then I let the game generate the rest when I start the Launcher to reinstall my Sims3Pack items. Nine out of ten times I can then start up my old Save without crashes.