Neapolitan Mastiff help?

I'm getting a neapolitan mastiff who is already 2 years old. I know that they are very stubborn to train and i'm pretty sure he is not house broken. I also know that his old lifestyle was an outdoor dog and he's very thin. ( i'm picking him up so that he doesn't get put down at a shelter). I'm hoping to get him trained well. Is there any recommended kibble and help. This is a big job i know, but i don't need help with yu guys telling me that, i just need some good hard facts that will help this dog have a better life. Also are there any recommendations on bathing him. I'm new to this large breed, but i have delt with other dogs before. Thanks for all HELP!!!