[targonrotts]

lines like scratch marks?
could be puppy nails that were not clipped and scratched the delicate puppy skin.
bite/tooth marks?
could be some rough playing going on with your pup usually on his back.
pimples?
could be puppy pyoderma, a little skin infection most pups get and usually clear on its own.
hard to say without seeing what you mean.
freckels?
could be pigmentation.

but all in all, joining a puppy socialization class and starting training, your pup should adjust fine. the more you socailize,train and expose and built confidence, the more stable your pup and enjoyable mate he will be.