It would be in the relay box under the hood near the battery.
The evaporator is in the A/C heater box under the dash.
The front blower motor relay is located in the fuse panel by your left knee. When you remove the cover, you will find a fuse block and 5 relays on the right of the fuse panel. The front blower relay is the last relay on the bottom
1997 van aerostar front heater blower guide
Not all models had a heater control valve. If it has one it's either right in front of the firewall by where the heater hoses go in, or else under the dash near the heater core.
YesYes
The distributor in a Mercury Villager is the round thing at the front of the engine with the six spark plug wires attached to it.
Front wheel drive
Bottom front of engine.
It is on the front of the engine on the end of the crankshaft.
In front of the engine, down in the "V".
At the front of the motor attached to the engine cradle.