How did Amber Volakis die?
Amber Volakis (Anne Dudek), one of the fellows he eliminated earlier in the season and, most importantly, his best friend Dr. James Wilson's girlfriend. She and House were involved in a bus crash, and she ends up dying from her injuries and complications from a flu medicine she was on.
Does House have syphilis?
As punishment as breaching the agreement, House and Amber are both forced into cleaning the beds of comatose patients. Kutner reveals that House has syphilis. House tells Wilson that he actually swapped his own blood with a patient with syphillis. Amber tells Kutner and Taub that House doesn't have syphilis at all.