Thanks for the feedback and glad you're enjoying the game.
Submerged subs are far too sensitive to gunfire right now, it is a bug getting fixed in the next update.
Yeah, there are some strange memory issues when re-starting a game session. Very hard to troubleshoot... The game is somewhat memory intensive so clearing the cache and reloading each time will make it run smoother and more stable, so it is probably worthwhile doing this.
For those escaping merchants, you don't *have* to get them all. If you can hit them hard and fast to begin with, letting those stragglers go will hopefully not lose you the war. Unlike Pacific Fleet, you're not expected to sink everything that appears in combat
