Do these markers have the bulbs installed?

Bulbs are not confirmed as included. Verify your existing bulb type and condition before installation — you may be able to reuse what's currently in your bumper.

Will these sit flush with my bumper, or do they stick out?

These are designed for factory mounting points, so they should align with your OEM bumper recess. Test-fit them in place before finalizing any fasteners to ensure they sit as expected.

Can I paint these before or after installation?

The clear lens finish is ready to install as-is. If you want to paint the housing trim, do that before bulb installation to avoid heat damage to electrical components — then let paint cure fully before powering on.