The special rules state that due to weather conditions, no aircraft, pilots, tanks, or tank crews are allowed.Since the starting units include two crewless Shermans, it would seem that tank crews could be included in the reserve deck to enable the Americans to re-occupy these units and fire their weapons. Is this correct?
The intent is that those two knocked out Shermans act as cover for advancing US infantry- any friendly infantry units gain the defense of the tank "wreck" minus 2- even if the tank is not crewed-- similar to the Tiger I "Wreck" Feature Tile. This should be more clear, but the intent of restricting tank crews in Reserves is to not allow re-crewing of these tanks. Mainly because the tank is partially knocked out and the weather is so bad it would just be sitting there immobile as a sitting duck for that Panther Turret emplacement to fully destroy if re-crewed. At least that was the intent.
Under these same conditions, can the M7 Priest be used as a strictly rear line artillery unit, which is unable to enter the map?
Yes, this is okay. Good question. It's a SPG, so as long as it remains off board on the rear line, that should be fine. Most of the deck will consist of rear line support units such as this or 105s for the US.