Well, corporal is the minimum required rank for serving on a Naval Ship. Below that, there is the Private. And yes, there is a handful of cooks and non-Naval staff (included in 'Operations'), although cleaning is largely automated. The remainer of your questions is answered in the new 'Background' thread I've just posted to keep the large amounts of technical information away from the character-related questions.
Edit: Missed one.
The launchbay is located on the front of the ship. Note that the Hades is not a 'carrier', so it only carries a limited number of fighters and support craft.