as already stated the MK4's mirrors will both move when you're on R, this also helps when you're parking in a bay as well as adjusting for other drivers (not that you would let anyone else drive your golf)
regarding the coolant, try taking the top off and giving the hoses around the radiator a few squeezes this should get any air bubbles out of the system, at which point top the fluid up abit, run engine on idle and check the level again.
it could just be a sensor though