1 year of full time RN experience is required at minimum to qualify for any of the specialties, such as ER or ICU. Ultimately, the decision to award you a specialty code is to a large extent at the discretion of the specialty consultant you interview with. A lot of times they don't like small, community hospital ICUs. To have your best shot, you need to get level 4 NICU. I'm really drawing a blank on where the NICUs are. I think there are 3: I know one is in Japan and I think one is in San Antonio, TX.
Med-surg exists at Lakenheath (England), Landsuhl (Germany), Elmendorf (Anchorage, AK), SAMMC (San Antonio, TX), Travis (Fairfield, CA), Eglin (Pensacola, FL), Langley (Langley, VA), Wright Patterson (Dayton, OH), Nellis (Las Vegas), and Keesler (Biloxi, MS).
Bonuses change all the time. You need to ask a recruiter.