If I skipped imp quest and went ahead exploring demon hall, can I do it later and also get the shop in the end?

For context, I currently on a RoW run and want to do sad ghost + RoW farming on F16 to simultaneously farming wands. I want to stay at Lv 17 so the bat can still drop some stuff. If you say "F18 have more shaman spawn rates", true but then I have to clean up some DM 200 which slows down the farming a lot. F17 already have spinner which will make me goes past the bat exp cap.

Edit: i got the RoW from hero's remain, so I immediately have RoW +3 at F2