You don't need operations specifications, however you do need Letters of Authorisations for a lot of things such as RVSM, MNPS, RNAV, MMEL, CATII/III, EVS etc etc.
You need to find out which FAA FSDO deals with aircraft based in your country.
While you are at it, take a look at SAFA requirements as they love N registered aircraft, and ICAO annexes 2 and 6, once you have that done, assess the complexity of your operation and search for a Safety Management System that corresponds to this complexity.
Finally, make sure that you have the European importation documentation available.
Is your boss actually paying you as a "one man do-it-all"?
Mutt