To be honest, I can't think of an equivalent English phrase for either of those.
Is "oh, just go on the roof and play with the pigeons" a phrase used to tell someone to leave you alone? Is it used as a joke to tell someone to engage in a dangerous activity (since they could easily fall off the roof)? If that's the case, an equivalent English phrase would be "Why don't you take a long walk on a short pier?"
Pigeons in the US are sold mainly by breeders; the birds are kept in either
aviaries or
coops. Sometimes folks sell pigeons at open air markets, but true pigeon fanciers recommend that you avoid these birds and buy directly from an accredited breeder.
It's hard to find a corresponding phrase in AmE for your "I am the dirt beneath your shoe" idiom, because, frankly, very few Americans are that humble.

Sometimes in jest a person will mock-protest a favor or kindness and say, "I'm not worthy!" But to be honest, such overt statements of humility are usually considered Far and Middle Eastern traditions.