1. Do Anja’s grandparents go to Theresienstadt in Czechoslovakia? What happens? How does Vladek find out?

Yes, the grandparents go to Theresienstadt in Czechoslovakia. The families are threatened that if the elderly aren't given up, they will take the entire family. Thus, they let them go. The grandparents are taken to Auschwitz.

Vladek also ends up in Auschwitz, but I need to go back and look for you as to when he found out the grandparent's fate.