Do these come with bulbs?

The units ship as lamp assemblies — bulb inclusion not specified. Test-fit first, then source bulbs if needed based on your setup.

Will I need fasteners or adhesive to install these?

Mounting hardware not confirmed in product specs. Inspect your vehicle's corner light bays before installation to determine whether you'll need clips, brackets, or adhesive backing.

Can I return these if they don't fit?

Check the site's standard return policy — these are brand new units, so condition won't be an issue if fitment doesn't work out.