Do the bulbs come with it?

Vanity fixtures like this typically ship without bulbs. You supply four bulbs of the wattage and base the fixture specifies.

What kind of bulbs does it take?

It uses four bulbs in the sockets the fixture is rated for. Check the fixture's rating label before buying, since the listing details don't state the base type.

Will the satin opal glass look yellow with warm bulbs?

Satin opal diffuses light evenly and takes on the color of the bulbs you fit. Warm-white bulbs keep the aged brass look; cooler bulbs read whiter.

How wide a vanity will four lights cover?

Four spread-out sockets cover a double vanity better than a two- or three-light bar. For a single sink, a smaller bar is usually enough.

How do I clean the aged brass finish?

Use a soft, dry or slightly damp cloth. Abrasive polishes and harsh cleaners can dull the aged finish.

Is it suitable for damp bathroom air?

Vanity bars are made for bathroom use over a mirror. Keep it clear of direct shower spray and check the fixture's damp-location rating if it sits close to the tub.