Will these plug directly into my factory wiring harness?

Yes. These are designed as direct replacements using your existing electrical connections. Disconnect the OEM markers and plug these in — no rewiring needed.

Do I need to remove the front bumper to install these?

No. Factory mounting points are accessible from behind the bumper panel without removing the bumper itself. You'll need basic hand tools and about 20 minutes per side.

Are the lenses permanently smoked or can they be modified?

The smoke finish is permanent and integral to the lens. If you need a different lens appearance later, replacement lenses are available separately through most BMW parts suppliers.