Are you referring to the northern part of the Crimea, or the east, as where to fight? The eastern port is Kerch, and that is the straits. The northern section is the Isthmus of Perekop. Again, I agree with your assessment, and would willingly give up guards in 1942 for a sizable army. I find it strange to give up Stalino without a fight, and I generally fortify and fight the hardest in the south in winter. Maybe I don't play to win enough, of maybe I am prejudiced with the slashing attacks across the Steppes, but I like to stay as far forward as possible. I find the easiest way to knock Germany out is to go the the south, removing Romania and Hungary and putting pressure to extend the German line of troops down south quite a bit. So, if I hold a bigger buffer in 1943 in the south, the easier it is to get a draw or a win as Axis, in my opinion.
As far as the German divisions go, they will have a shell put on the western map, and they sit there for 4 turns before you are allowed to move them. They will cap at 80 morale, and will suck up replacements that would normally head east into units. He lost them soon enough to most likely get all 4 back up to 80 morale. And, if he uses the winter before the summer for morale building exercises, they should all be between 80 and 85 morale when June of 1942 rolls around.