Please read the TWoS thread, there are a lot of special things to consider and do. SH5 is a nice but difficult game. If you don't read you will have dozens of questions before enjoying the play and tired people to answer same things for the x time ...
For TC, the x64 limit is normal if ships are nearby, I can only guess it's because of stability reasons. That's it. And there is more about TC, just read the thread.
To get out of ports quickly, you can use the Automation feature and increase sub's speed to half engines (10 knots) while still using TC.
To break a friendly contact, it's not that difficult and shouldn't take too long at x32,x64.
Good Hunting Captain,
