About training and atlantic mods

[mariokartjkl]

I've a couple of questions :
Okay guys i've bought sh4 and the uboat expansion on steam. So I've installed both (for get the 1.5 patch) but i don't understand why on steam i can start 2 games (sh4 and the expansion) but if i start sh4 i can start the u boat campaing from there. Anywhere I've installed RSRS with TMO for Pacific campaing but now i want start an atlantic one with u boat. So Are there any mod that I have to install for a better experience with u boat in Atlantic Campaing and can I install mods for pacific and for Atlantic together?If yes how? If not can I do 2 installation with steam?

Last thing : Are there any good mods that add tutorial missions?Or some mods that add some guides in the game?

Thank you for all and sorry for my english