http://www.subsim.com/radioroom/showthread.php?t=174225 One of those will give you more messages from BDU, and theres a bunch of (really) cool other stuff there.
I cant awnser the second part, I tend to use impact for SAFTY RASINS
For the motor boats, I gotta agree with you. I think its just with the way GWX works, it raises the HP value of all ships by a lot and makes flooding more important. Of course, hitting below the water line on one of those things from range with anything but a glass seat is a feat
About the shells, well, theres no reason to use AP, as if you engage a target that would require AP (Crusiers, battleships ect) You are using the submarine very wrong >>. Starshells you dont have because the darkness is your best friend, lighting up the world around you, even if its a lone merchant it can be silly. What if theres a good ol' destroy taskforce just out of sight? Youll (probably) end up like this guy here :
and we already have enough Uboats lost D:
Hopefully Ive been helpful. Though last time I tried to help someone I got slapped.... so Im going to go hide in the nearest corner. Bai.