[LT Guppy]

The length of service doesn't really have an impact on whether you should go officer or enlisted. People do both and have full careers.
It really depends on what you want to do. Officers tend to be more management-type positions (lots of paperwork and meetings) whereas enlisted sailors do the hands on work.

Advancement for officers actually isn't like that. You make O2 automatically at 2 years and O3 at 4 years, 1 month. After that it's based on a selection board. Most people are O3s for 5-8 years (you do a shore tour and at least one sea tour as an LT). Advancement right now is actually pretty good.

Reenlistment bonuses come and go.

If you're nuclear qualified you may retain your nuke special pay.