Does it plug in or need wiring?

It is a hardwired fixture. It needs a wall box and mains wiring, so plan on an electrician unless you are replacing an existing sconce.

Usually not. Check the socket type and wattage the fixture takes, then pick bulbs to match; a dimmable bulb only dims if the wall switch is a dimmer.

Can it be used in a bathroom?

Only if the fixture is rated for damp or wet locations and placed outside the zones near the tub and shower. Check the rating before installing in a bathroom.

How high should it be mounted?

For bedside use, roughly eye level when sitting, around 48 to 60 inches to the center. For hallways and stairwells, follow the electrician's guidance and keep it clear of handrails.

Can I put several in a row?

Yes. Sconces are commonly run in pairs or evenly spaced rows on one switch. Space them consistently and confirm the total wattage stays within the circuit.