I've watched several videos and searched the forum here for the steps to dewinterize. This includes the official one from Grand Design (https://youtu.be/xtQawh-01kc) which does not reference using the suction tube to run clean water through the water pump but rather runs water using city water. Other posts and videos vary on which order they run water through the pump.

My questions?
1. is it necessary to use the suction tube to pull water through the water pump when dewinterizing?
2. If yes does it matter where in the process that happens?
3. Can you dewinterize without city water by using fresh water tank?
4. Do you have a favorite video or checklist for dewinterizing the plumbing system?