Note that Lena is 'not' doing a show in front of the Berlin Wall- these are separate elements for place-setting. Thus, your angles do not need to be bang on.
Subsequent books will feature the main characters of those books in a similar format.
"Checkpoint Charlie" was a physical section of the Berlin Wall. The actual Berlin Wall featured concertina barbed wire, landmines, watch-towers and search-lights.
If graffiti is prominently featured, please ensure that it represents real-world samples. If that is a tall order... just please make sure it isn't in English.
Lena Schindler is in a punk band- not a porno. She doesn't need to be (and shouldn't be) scantily clad. She is a 17-year-old who is woefully out of her element and grasping at concepts she won't fully understand until book 6; but I still want to communicate a capable, wild woman, despite her naivete.