You must stop the playbiting now. The best way to deal with it when he starts is to yelp or cry and turn away from him and ignore him. Do not touch him or react with him otherwise you are effectively "rewarding" him. Hope you can understand that. Only respond to him when he is calm.
If the play biting is very persistent then as it begins quietly take him out of the room and close the door on him for a few minutes. He will learn that playbiting ends the game eventuallu.
When you allow him back in the room, greet him pleasantly.
As for the needing to be let out 5.00am for a wee - he may well have got into a habit that is quite hard to break.
Hope this helps