Generally a Maltese cross is used where you would expect a swastika. With pictures of German combat aircraft, there is a featureless diamond on the tail of the aeroplane. I assume this is to allow the game to be freely sold in countries where the display of Nazi symbols is illegal as well as offensive. The AI is, as mentioned, capable. I was particularly surprised by the coarse-grained damage reduction.
Most units have three steps, with some weaker one and two step units.
There is no consideration of fatigue, disorder, or morale. When a replacement step is assigned, the unit loses its attack opportunity for that turn but can still move at full speed. This leads to odd effects. Panzer divisions can keep attacking every turn, just omitting the odd weakened regiment from the attack for replacements as required, while a defensive line can keep falling back, replacing losses as it goes. As unused replacements are lost, the pace of the offensive is dictated by the number of replacements available next turn as much as anything else.