For contact reports this helps;
http://www.subsim.com/radioroom/showthread.php?t=211613
I've found that you can sit at a depth of 27-28 feet (decks awash but still surfaced) and let an escort get within 3000-4000 yards without him seeing you, even in daylight with perfect visibility. Main trick is to set the periscope or TBT on one of the ships (not an escort) and hit the L key to lock the target, THEN send the contact report and submerge - you'll get the reply at periscope depth, you can receive but not transmit while submerged.
As for the sudden death, it's irritating - no damage and then destroyed by a single attack. Personally I hate that so much that I cheat.
Silent 3ditor;
http://www.subsim.com/radioroom/down...o=file&id=4489
Was made for SH-3 but also works for SH4. Open Data\Submarine\SubType\SubType.zon (whatever your favorite is, for example Data\Submarine\Gato\NSS_Gato.zon if the Gato is the one you like best).
Using the Gato as an example, I open NSS_Gato.zon in Silent 3ditor and find;
37: CollisionableObject
ArmorLevel=25
HitPoints=450
CrashDepth=277 (actually CRUSH depth in meters)
CrashSpeed=2.67
Rebound=0.45
No idea what effect rebound has on anything, but change the hit points and the CrashSpeed;
37: CollisionableObject
ArmorLevel=25
HitPoints=999
CrashDepth=277
CrashSpeed=0.1
Rebound=0.45
With those numbers you get a bit less than half the normal damage, adjust to taste. CrashSpeed is how many hit points you take per second when below crush depth, and crush depth is actually a percentage of max depending on how much hull damage you have. If max depth is 500 feet and your hull is 50% damaged, your new max depth is 250 feet, and you lose 2.67 points per second below that depth. Original total hit points 450, lose half of those in the attack you have 225, go below crush depth for 2 minutes and you lose 320 more points, which means you're dead. Changing just those two values means 999-225=774 remaining, lose 0.1 hit points per second and after 2 minutes below crush depth you've lost 12 points and are still alive.
It always seemed pointless to me to have a damage control team if they have no chance to actually do anything, so I cheat.