I'm not sure about the patcher not finishing bit, Noenmity, but I'm pretty sure that the first bit is addressed on the actual Sims3 website forum.  The advice given is to delete the Version.tag.  Some folks say it doesn't work though, in which case others reply that an uninstall of EADM (and reinstall, I suppose) makes it work.   Perhaps this info will help you.

I think the party guests run to the sim who is hosting the party (the one who used "Throw Party" on the phone), so if you have that sim outside they should throng outdoors.  Perhaps place some empty tables outside so they can deposit their lousy hot dogs without having to jam up your indoors.

I had the error 12 and 13 problem--including .bad saves, crashing, and neighborhood loss--about a month ago and noticed that it only happened after a long gameplay session--I'm talking about 7+ hours.  Neither the frequency of my saves, or the length of time between them seemed to have any effect on my tendency to get error codes.  So on days when I intended to play an indulgent amount I started exiting the game after 6 hours or so and then restarting it.  Since coming up with this strategy I haven't had a 12 or 13 error code since.  Perhaps this could be helpful for the rest of you.

EDIT: I play a vanilla game, no CC except for store items I used my points for.  I have 4 gigs of RAM.  My neighborhoods were in the 55mb range (approx.) when the errors started.