First, it would benefit you to take the time to ask your questions using proper punctuation and grammar. First, it will give others the impression that you are a smart, capable young man worth helping. Second, it will allow others to actually understand what you're trying to ask.
There are several options within NUPOC - Naval Reactors Engineer (NRE), instructor, submarine officer, and SWO(N). You should research the differences and clarify which program you are trying to enter. That will allow people to answer your questions about long-term career goals within the Navy.
SWO(N) alter between 'smallboys' (DDGs, CGs, FFGs, LCS, etc) and carriers. On smallboys they work in a non-engineering department and stand JOOD/OOD (con the ship), on the carriers they work in the reactor department and stand watch supervising plant operations. If you are male then SWO(N) is probably not an option for you through NUPOC. You would have to apply for an NROTC scholarship and try to get selected during your service selection, but that is also up to the needs of the Navy.