1.- Never heard of that bug
2.- its an upgrade bug which causes the AI to eventually spam the same units(i.e Partisans)
3.- Its hardcoded, the Player can't have the Russians retreat or recrew heavy weapon systems (AT guns, Mortars) Dev team is fixing it soon.
4.- I believe that they are aware of that.
5.- the AI is plus 1/2 so Normal is 1 + .5 , so its still normal but not easy.(I think so atleast)
Oh and the Moderators will probably close this since there is no version tags, add
[1.1] or whatever version you have to the name.