Sorry for the late reply...Yes, there are many boat tours of the Spree river. We did not take on, but next time we are in Berlin, we are planning on doing a boat tour.

Nem kell előre időpontot foglalni!Nyitvatartási idő (opening hours) megnézhető a honlapon és online jegy is vehető!

All of the museums should be open with the exception that the Pergamon altar is closed for several more years, but the rest of the Pergamon is open. Don't miss it. To compensate, there is now a separate Pergamon extension that replicates the altar using a movie style screen. Its huge and 360 degrees. Don't miss that either. It is a short walk behind the Pergamon itself. Get to the museums early to avoid lines. The museum pass is a good deal if you are seeing several. Audio guides are free and superb.

In some museums, like the Pergamon, it’s included. Some charge a little extra for it.

Machen Sie eine Onlinereservierung und danach machen Sie die Zeitreservierung. Wenn nicht viele Besucher da sind, dann brauchen Sie die Zeitreservierung nicht und können zu jeder Zeit das Museum besuchen. Sie werden begeistert sein! Herzliche Grüße!

museum island is free to walk around and tickets to enter the various museums are bought at the various museums.

Mi dspiace ma non posso aiutarti, forse e il caso di lasciarlo in hotel

Not sure, I bought at the door. If you don't have access to printer than you can't print. Other places I have used email tickets.

Sorry, no idea. However, I have found elsewhere that mature students don't always get student concessions despite holding a valid student ID card.

Nothing more that I can add of value. WandererPilgrim's excellent recap said it all. Lots of walking and it will likely be cold at this time of year.