I am no BBQ Guru guru - but I do use one on my uds.
When I had 3 plugs - I would occasionally open them all for lighting (use weed burner method). My current UDS only has one hole - and it works fine.
I use a weed burner for lighting. I light just enough for the guru to catch and bring it up to temp. The weed burner preheats the uds, so it is a bit of trial and error. I do stick burns, which complicates matters a bit - they will ignite and spike the temp, but not have enough coals to stay lit once it is dampened down.
I use a drilled out tire stem as a grommet, it is just below the meat rack - I also have a second mechanical probe to double check temps. You don't have to drill out the stem much for the pit probe, you do have to shorten it and drill it out a bit more for the curved meat probe (I have 2 stems in mine, the second is 2" above the meat rack).
For the most part I keep my exhaust fairly closed - and let the fan force the air through (I am not using the guru fan, and mine does have a little draft when it is not running-mostly closing the top of the pit helps with this.