For the first one, yes they are mutually exclusive because:
- If event A happens it is impossible for event B to occur
- If event B happens it is impossible for event A to occur
For the second question, they are not complements.
To be complements the sum of the probabilities of the two events MUST add to 100%. In this situation, if you toss two coins, you can also get ONE head and ONE tail. In short, they are not complements because Event A + Event B do NOT equal 100% of all possible outcomes when tossing two coins.