A auto vent
Yes BUT not an outside wall
Vent through roof
You should not have to clean a vent on the roof. unless you are trying to clean the waste line to the fixture below. Then you would send plumbing rods through the vent on the roof.
In plumbing the roof vent should be a min of 4" to prevent hoarfrost
Yes, it does
Water Jetting works best
Yes a vent pipe can be painted AFTER it has passed inspections and some localities want the piping labeled "Vent"
Depends on the size of the vent and what city you're performing the work in. Speak with a plumbing inspector for that city and tell him the size vent and he will tell you the maximum length. To determine the size of a vent you have to know developed length of pipe and fittings and the fixture units connected
One that vents one fixture
NO!
the plumbing drain vent is not installed or poorly installed.