The things already on your list and Chuck's list will eat up at least three days. So much to do, so little time...
For hobby shops, my favorite (in 1986) was always on SchlossStrasse, Called Werken Spielen Denken, right at the U-Bahnhof. There's a downstairs entrance. I think it was Linie 2 but it may have changed since the "Wiedervereinigung". At any rate, take the line that ends at Rathaus Steglitz, The station you want to get out at is two before that. Or if you're on the street, ask everyone where the PilsTurm is-they'll know. The ground entrance is literally under the PilsTurm, which has a nice restaurant by the way. I took my three day pass from Afghanistan to go back there in 2003, an it's still a great shop. Also one on GuentzelStrasse, off of Bundesallee.
Back in the day, there were also several model railroad shops around Alexender Platz, which would be another place to visit in its own right, along with a ride up in the FernsehTurm, the second highest manmade structure in Europe, with a revolving restaurant in the globe portion.
The Russian War Memorial Chuck mentioned is worth a look. There are two T-34s flanking it. Access used to be limited. My friend and I caused an incident when we "accidentally" followed a tour bus through the gate on our motorcycles.
There is/was another memorial in East Berlin dedicated to the "Victims of Fascism and Militarism" where NVA soldeirs performed a very impressive goose-stepping changing of the guard. I'm sure they've probably done away with that portion... Anyway, it had an eternal flame, (not to be confused to a similar one in Charloten burg dedicated to JFK-also something to see) so I would assume it's still there.
Our old Barracks, Macnair, has long been shut down, but several German Nationals who worked for the Army have set up quite a nice museum there. MacNair is in Zehlendorf, near the Ford plant. It think it's bus line 87 now. Anyway, for good directions, talk to Lothar Bardeck. His email is:
[email protected]It's only minutes from the Allied Museum, which used to be our old theater.
If you';re a counter-culture type like me, the bikers all hang out at the SpinneBruecke on the AVUS. Any biker in Berlin can tell you how to get there.
Have fun. No matter what you do, it's still the greatest city in the world, even if you can't f with the Russians any more.