Having read the OP plan i believe it cannot be done. He will find himself in so many traffic jams, will enjoy plenty of border controls, might not be allowed to take the car rented in Germany to Poland and other eastern places and will experiene great roads in Poland.
The plan itself creates somes questionsmarks on my face. What "Wall" does the OP expect to see in Berlin? And a local WWII museum? I am not really aware of any. And driving from Berlin via Krakow to Munich in about 36 to 40 hours (without any sleep) and crossing borders several times seems to be difficult to impossible. Could continue with that.....