Will these plug directly into my truck's wiring harness?

Yes — these assemble use the factory connector. You're connecting into the same electrical points your OEM lights used. No rewiring or adapter harnesses needed.

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

Access depends on your truck's specific configuration, but these bolt at factory attachment points. Most installs work with basic hand tools and access from behind the bumper opening. Consult your service manual for the exact sequence if you're unfamiliar with your truck's headlight removal.

Are the bulbs included, or do I need to transfer mine from the old headlights?

Bulbs are not included. You'll transfer your existing bulbs from your current headlights into these housings — same bulb type, same sockets.