Will these mount at the factory holes with no drilling?

Yes. These use existing mirror mounting points — no frame modification or holes required.

Do the turn signals work right out of the box?

The housings are built for signals, but you'll need to run wiring to your vehicle's turn signal circuit. Refer to your truck's service manual for wire routing and connections.

How do I adjust the glass once installed?

Manual adjustment uses a cable system controlled from inside the cab. Pull or push the control to angle the mirror glass where you need it.