I brought my exboyfriends female chocolate lab into the house when Rocco was 8 months old. He like her but played very rough. I just made sure to watch them when they were together. I also made sure that the puppy spent time in her cage alone so Rocco and I could have our time together still. We never had food issues but he constantlly snatched her toys, bones, and treats. Stupidly I let him do this now she protects her stuff, which really isnt' my issue anymore but I feel a little (very little) bad about the fact that Rocco helped reinforce her guarding her stuff.
When Rocco was almost two I got Maia, OEM, and he knew exactly what to do with her. Now they play rough, neither has ever gotten hurt (knock on wood).
I would get your big puppy around other puppies and see how he does. Get him used a small animal being under, around, on top of him. Plus little puppies bite and bite hard. I have heard the older dog should mildly correct the puppy but not snap it's head off. It is tough having two puppies but well worth it, they get to grow up together.
But be careful, you will now want a new puppy every 10 months and it is hard not to get one. I foster puppies for a rescue and that gets my puppy fix in so I don't crave one as bad. Though I have another Mastiff when I breed Maia next year.
I hope this helped.