You need to talk to an officer recruiter to get exact information. It must be a recruiter for officer programs or you will not get the best information. For OCS, I think it’s usually 4+4. 4 years active duty and 4 years selected reserve (non-drilling but able to be recalled to active duty). It also can vary by warfare designator.
- Tuition Assitance will not help. The rules changed several years ago and it can only be used for undergraduate classes towards a first bachelors.
- It is correct that if the Navy didn't pay for your first degree (USNA/NROTC), then you get the Post-911 GI bill after your four years. It is quite generous and includes a housing allowance.
- The Navy does send folks to Navy Postgraduate School in Monterey, CA for Master's and occassional PhD degrees. These are typically after 6-8 years of service. There is also a permanent military professor program but it is highly competitive and is again for officers around the 8-10 year mark, maybe 12 years.
- You need to join the Navy because you want to be a Naval Officer or it will be a waste of time and you will be frustrated. Which warfare communities are available through OCS also varies. There have been times when the only option was supply officer. Not a bad choice but not one that will get you to NPS for a Masters in a STEM field. Other times you could go aviator or surface warfare. Talk to an officer recruiter.
- NRTOC requires certain majors and a certain math/sciences. Check with the recruiter. You may need to make sure you have certain classes, such as calculus, physics, and chemistry regardless of what your degree is.