The space slug is probably one of the worst scenes in the original trilogy.

TESB would be a better movie without it though you lose some character/story development on the Han & Leia arc if you cut it and all of the attendant scenes wholesale.

I'm a fan of the added breath stuff. Lived in Wisconsin my whole life and trust me, you don't see your breath all of the time when you're outside in cold weather. Nice touch of realism but it also strikes me as something you could slowly drive yourself nuts doing.