Buoyancy control is the first scuba skill that should be taught. In my class that is in pool session 2. Mask removal and clear along with equalization is done in the first pool session which is snorkeling and skin diving. Along with snorkel clear that translates to reg clearing. Only difference with that is now you CAN breath in with the reg! Buddy breathing is a required skill in my OW class in pool and OW. Both stationary and swimming. I also do the buddy breathing gear exchange with OW students in the pool as an additional task loading exercise.