The rules that govern the way that vehicles approach parked aircraft varies from locale to locale, it is governed by local rules and regulations.
true
If it's a refuelling truck I'd park it just in front of the wing.
Unless it is a service vehicle that is in use for maintanence, you should never park directly in front of an aircraft.
'Park' or 'low gear', depending on the vehicle's transmission.
When the aircraft engines are off
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
A control tower that controls aircraft landings and launches and where they park.
you must apply the brake fully to put your vehicle in park
Aircraft park on the flight line.
A terminal in the Airport sense is a place where aircraft park while passengers get on and off.
Legally - at all times the vehicle is used on public roads. Practically - when you want to park on an incline.