Welcome to Subsim.
1. Kaleun in the Kriegsmarine was abbrevation for the captain of the Uboot who usually held the rank of Kapitanleutnant.
You can find more here:
http://www.uboat.net/special/abbrevat.htm
2. I think yes. You should keep your engines at 75rpm which give you a speed of 1 kt. This has to be set manually as the "silent running" option of the game sets speed to 2 kts. You have to use "silent running" to keep the noise down: it stops the pumps and the reloading of torpedoes.