The first one is that *SPOILERS* after completing the companions quest line, Skjor was just walking around Jorrvaskr even though he died in one of the early quests. He still says "You need to prove yourself, whelp." even though I'm the Harbinger. I can still get jobs from him as well.
The second one is really odd but I'll describe it the best I can. Sometimes when I switch from dual wielding one handed weapons to dual wielding spells my character's right hand will be down at his waist and his left hand will be held up like there's a spell in it, but there isn't. I can't lower my hands or use any spells or weapons. This rarely happens, but it's really annoying when it does.
The third is that when I try to load a previous save it'll most of the time be stuck on an infinite loading screen.