Without actually seeing the behaviour, the pup is being a pup. The dogs he is 'picking' on should eventual put him in his place. Its part of the socialization process.
What should you expect? Everything! All kinds of love and fun. All kinds of scratches from those nails and razor sharp puppy teeth. Lots of laughs from the antics and tumbling. Lots of frustration trying to train for that reliable recall. Lots of new friends coming to love your pup. Lots of terror when things in the house are destroyed. A nice friendly, and competent vet to keep the pup healthy. Lots of big vets bills from the vet keeping the pup healthy. Debates on what food to feed the pup and when to switch to adult food. Lots of messes to cleanup when the stomach gets upset. For every minus, there will be many pluses.