A few quick questions

[LeBueno]

Well, I am playing my first ever career. Many questions pop to my mind all the time, but I usually find out the answers from here. Now I have a few questions where I can't find answers, and so I "had" to make this thread.
So, I am in my type VIIB somewhere in the North Atlantic, Northwest from British Islands. My mission was to move to AL36 and patrol for 24hrs there. I'm in the point where I am already returning from my mission. I have succesfully sunk a little over 10 tons of British ships on this mission (3 merchants). Here are the questions:

1) People talk about ending their patrol by simply pressing esc and clicking something like "return to harbour", is it disabled with harder realism settings (I have 74%)? If its not, do you guys use it? Feels for me as cheating.
2) Do I have the fuel to go back? I have currently about 40% fuel left, and I am still somewhere at AMXX. I don't think I ever had the fuel to do such a long trip?
3) How much freedom did the U-boat captains have? I mean, when they got orders just to go to a grid XX and patrol there, could they just attack what ever they wanted when they were sailing to the grid? Did they have the freedom to just go in to some harbours to blow some warships down? I feel a little guilty when I waisted time to kill one merchant on my way there. But after all do BdU care where I sink enemy ships if I am sinking them?
4) Best tactic to deal with enemy planes? Immediate crash dive or try to shoot em down? It seems that my sailors are doing some lazy job up there as they spot incoming planes so late...


I'm thinking also that would it be good to make a sticky thread named something like "quick questions" or something, as it feels stupid to make a new thread for all the little questions what come up in your mind. In example, Hearts of Iron 3 forum has a thread for quick questions, its very useful as people can post their questions there and get a answer and no "unuseful" threads has to be done.

Thank you for your answers.