For # 1- I'd say "what were you waiting for yesterday? "? instead of just a simple past tense.
# 2 is awkward. I don't think people really speak that way.
However, there are contexts where "yesterday" can be placed at the beginning or at the end of a sentense. i .e. I went to a movie with Mary yesterady, or yesterday I went to a movie with Mary. That's why Grammar rules are only guidelines. By memorizing them, it will only get you more confused.