Honestly, most expectation dates are arbitrary, especially on ugl goods. Nothing wrong with using a vial like that as long as you're the only one who has used it. Cool dark place, some guys suggest keeping the vial upside down or on its side to keep the stopper from drying out. Probably not that necessary.

As long as it's within the expiry date and not contaminated, then yes. Store in a dry place at room temperature.

cool dark place, not the fridge. There's no problem with using an opened vial even if it's past the exp date. Exp date is more for potency I.e. an expired product of the sort would just lose some of it's potency.