In regards to AI detecting the player.
There really is no need to reinvent the wheel:
http://www.subsim.com/radioroom/showthread.php?t=111395
Also, feel free to blantantly take AI sensor tweaks from my mod and apply it to your own game if you want. If you don't like my tweaks, theres also a harder escort mod by NVDrifer i beleive. Check the mod listing sticky post in the mod forum for link.
edit:
as to AI behavior's such as coming to a dead stop after a torpedo attack or convoys slowing down the speed of the slowest ship is beyond the ability to fix by a mod. That can only be patched by Ubi.