The answer to all questions is “yes” and there is a discussion here with various other people attempting to do this.
The only “no” is that currently Loiter mode doesn’t support using the lateral thrusters to keep the vehicle in place in all directions. This means the vehicle tends to move around a little bit especially when the water is still. In my tests though even without the use of lateral thrusters the buoy stays within 2m of the target position.