Unless it is a service vehicle that is in use for maintanence, you should never park directly in front of an aircraft.
If it's a refuelling truck I'd park it just in front of the wing.
no
'Park' or 'low gear', depending on the vehicle's transmission.
25 ft in front, 200 ft behind
When the aircraft engines are off
true
It is illegal to park a car in front of a fire hydrant.
25 feet to the front or 200 feet to the rear of the aircraft
When an aircraft's engines are running, you must not park closer than 25 feet in front or 200 to the rear
When an aircraft's engines are running, you must not park closer than 25 feet in front or 200 to the rear
The rules that govern the way that vehicles approach parked aircraft varies from locale to locale, it is governed by local rules and regulations.
25 feet to the front, 200 feet to the rear