Yes the D80 has an internal motor drive. I have no problem focusing/metering with my 50mm which is not an afs lens.

The vignetting on the 18-135 only occurs at 3.5 to 4.5. Seldom get it at 5.6
Its a known issue that can be worked around or even used once aware of it.

KEH is a good place to look for used. Cameta sells re-conditioned.
Shop for deals but make sure to check the camera dealer feedback forum for dealers to avoid.