[TorpX]

Hello Captain!

In real life, wouldn't the captain of the Snapper in this situation be required to go and rescue said survivors?

No. Captains and crews were expected to prosecute the war, so mission and the safety of the boat came first. Sometimes, one or two survivors were picked up (usually for intelligence purposes), but this would not be attempted under dangerous circumstances. There really wasn't much extra space in the boats anyway.

In real life, could a world war 2 era sub actually maintain depth without its engines working? I believe I have read that depth keeping in that sort of situation would be impossible ...

You're quite right about the need to keep moving. Depth control is accomplished by use of the dive planes, and they require the flow of water to do their job. If the sub was motionless, you would lose both steerage and depth control. Usually, a sub making an attack would be moving 3 to 4 knots (for a periscope approach). Too little, and the sub might broach after torpedoes were launched, too much, and the periscope would vibrate and compromise their view.

Don't worry about not knowing much about submarines. This game tends to be addictive, and many become highly knowledgeable about submarines.