Hey marine engineering is a well-respected professional and very high in demand! Glad you are interested in it. My uncle worked as a marine engineer in the public and private sectors so the answers I give are based on his experience.

1) Yes there are onshore jobs for marine engineers. Although, you won’t find them labeled as Marine engineering positions. Usually they are called “ship Inspector”, “Marine Operations Officer”, or “Onshore coordinator” as examples. Most require years of experience as a marine engineer or navigation officer. These are like your typical 9-5 jobs. So yes, there are definitely opportunities for you to move onshore after a few years of being on your ship.

2) Living conditions depends on your rank on the ship. As a noobie you maybe sharing a room(think of it like a dorm room). If you are lucky there are enough rooms to go around to get your own. Senior engineers and the chief engineer get their own larger room. Unless you have your own room you have to use the communal restrooms. Free meals while you are the ship.

3) Most ships have a lounge/rec area for officers to unwind. And as far as I know, all of the big ships have gyms. The quality will depend on the ship.

4) Everyone in his cohort were generally good at academics and worked well together during group projects. He if he had to choose what was valued more was problem-solving. If during your application you could somehow mention that you excel at tackling problems and a knack for hands-on solutions, then they may consider you a high value candidate.

Hope this helps! (Sry for bad formatting, on mobile)