It's quite an exciting time for you, big step. What do you want to know?
In general Bristow is pretty good on guiding you through all the paper work, visa applications, and setting you up with housing, car, etc. once you are there. Being a US resident you won't even have half the hassle anyone requiring a visa would have anyway.
It's always a good idea to do some home study and thus safe time & money later on. Get yourself a copy of the "FAA Rotorcraft Flying Handbook" (book or free download on faa.gov) and Wagtendonks "Principles of Helicopter Flight" for starters, that'll keep you busy for a while
