Rennet, Pizza

Question

Your recent clarification about cheese has triggered more questions: 1) Is animal rennet a problem in cheeses that do not require supervision, considering that it is a very tiny amount of the total ingredients? 2) Since you say that mozzarella cheese does not require supervision (only kosher ingredients), could a vegetarian pizza (with kosher but non-hechshered mozzarella) from a non-supervised restaurant be kosher? Thanks again!