Max is adorable!!!
My dogs are constantly wrestling with each other--it's just how they play!! I can tell if they are about to get mean--usually if there is a treat involved They fight over toys and bones, but once one of them gets it, they other forgets about it!!
Getting him neutered is the best idea. I don't know how much it will help with the playing, but it is the best thing to do for him. Our Shiba wasn't neutered when we got him, and he marked everything, including my mother-in-law's pom when she brought him over Walks with him took forever, because he wanted to pee on everything. Now he has calmed down a little, but most importanly, he doesn't mark everything.
Good luck with Max!!!