1)
What is "b'Geros Kimham"?
1.
Targum Yonasan: It is a Geros (Metzudas Tziyon - dwelling) that David gave to Kimham ben Barzilai ha'Gil'adi. Rashi - this is when David returned from fleeing Avshalom - "Iti Ya'avor Kimham" (Shmuel II, 19:38-39).
2.
Radak: It is the place where Kimham ben Barzilai lived. Perhaps he built it and came to live there; therefore it is called on his name.