1) I use incident metering at least half the time, and sometimes all of the time.
2) You can use incident light measurement if you are able to move the meter to where the light hitting it is the same as the light hitting your subject. So even if you cannot get to the subject, you may still be able to use an incident reading.
3) To the best of my knowledge, I've never read anywhere on APUG where someone has recommended using an incident dome to take a reflected light reading. Where there is some dispute, however, is whether to use a dome (or something else) when an incident reading is taken, and whether it is better to point the dome at the camera, or at the source of light.
For someone new to using a hand meter in incident mode, I would recommend using the dome and holding it at the subject's position, pointed toward the camera.