Hi Full Salvo, and welcome aboard!
Both of the points you raised where in GWX 1.3 in a basic way. There were enemy subs that you had to keep an eye out for. You did see AI german subs heading into port as you were leaving. There were wolf packs, but they were a little limited in what they could do.
From what I've been able to gather, there has been a great improvement in the GWX 2.0. The creators of this wonderful mod may tell us more, but then again, we will find out in the near future, won't we!