When I played around with dji way points I changed the altitude of each recorded point. My p4p followed both the track and the altitude. I didn't try to alter anything while flying the recorded path. I'll try that when the rain stops.
No. Each recorded way point will use both the altitude and direction it faced at that point. You cannot manually change altitude while flying that mission. You can edit them, but while mission is active it will fly what you initially set.