A little game play questions
 

I am patrol 2 after taking on the mission for British east coast. Day 10 into the patrol, I used up all my torpedoes and shells. I also finished patrolling the grid. Should I RTB? Find the nearest port to refit and come back out? or simply stay on station until Dec 1, the last day for East British coast mission? I just don't want to RTB then find out I didn't complete the mission.

Do whatever you want. Mission success is purely time based in TwoS as far as I have understood. Completing side missions will give you morale points but apart from that there's only one thing that matters: tonnage. Sink as many ships as you can wherever you want. Those missions are more like a suggestion. If you want to sink ships anywhere else, feel free to do so.

If you want immersion... you would stay out for 2 weeks and act as a weather boat!

It'll be interesting if you do other things such as laying mines, inserting agent, photo recon etc instead of being a pure tonnage game. Just another question, how to get promo points fast? Right I sank 7 ships in one patrol, totalling 30k tons, but I got 0 points. It seems only completing side missions would give you any point.

There is spy missions!

Btw, how do you prioritize your promo points. I am thinking about getting the sonarman to max out then navigator, chief engineer then torpedoman. What are your thoughts on this?

Chef and Boatswain! They slow down the morale decay in the game.

You can divy up the points between others, but be sure to put some in the ones I mentioned.