Can I take photos while filming.  It seems to stop the film to take the photo.
Also. When lowering altitude,  do I need to avoid pulling the stick all the way down.  Will this cut the  motors out or does that only happen at zero altitude

Holding the stick all the way down WILL NOT stop the engines unless the stick is held all the way down AND the aircraft DOES NOT descend for 3 or more seconds (i.e. on the ground).

I have descended holding the stick all the way down several times.

The only operator command using the sticks that will stop the motors is the Combined Stick Command (CSC) outlined in the manual