What you are considering attempting is a very difficult test: open groove on small diameter, thick wall pipe in 6G. This is the kind of test that most professional pipe welders sweat over when they have to take it. I doubt any newbe will be able to pass visual inspection much less x-ray if you just jump into it. Even if he does pass visual, I can just about guarantee you will see every flaw including porosity, inclusions and lack of fusion in the x-ray.
I recommend you save the 2" pipe for later. Concentrate on producing sound fillet welds on plate in all positions including vertical and overhead. When you can do that well (pass visual inspection and a bend test), go on to open groove welds on plate with a backing bar in the same positions. When you can do that well, go on to open groove welds on plate without a backing bar. When you can do that well, move on to pipe.
Start your pipe practice with something reasonable, say 8" or 6" pipe with around 3/8" wall. You want something thick enough to be able to do a root pass, hot pass, at least one filler pass and a cover pass, and large enough that you can ease into constantly changing your angle. Do 2G (pipe fixed in vertical position) and 5G (pipe fixed in horizontal position) welds until you can do them well. Then do 6G (pipe fixed at 45 degree angle). Work your way down to the 2" pipe.
The Horbart Institute has a whole series of books on plate and pipe welding that explain the techniques used. Absolute best book on pipe welding is Pipe Welding Procedures, 2nd Ed. by Rampaul. First edition will do if you just care about stick welding.
If you have a DC machine, use 6010 for the root, otherwise 6011. My guess is that you will have to use 1/8" electrodes on the test. But check with you provincial government to make sure. It used to be traditional to follow the root pass with a hot pass using the same electrode. Now some procedures are calling for the hot pass on a 6010 root to be done with 7018. Find out what the test will use. But practice hot passes with both electrodes.
The x-ray test isn't concerned with layers. There will be criteria specifying the size and quantity of defects. Stay under and you pass. Go over and you fail. Although you didn't mention it, there is bound to be a visual inspection first for excess reinforcement, undercut, underfill, suckback, lack of fusion, overlap and porosity. Fail visual and you don't even get to x-ray.
Check with the provincial government to see what the fit up should be. Otherwise use a 75 degree included angle for the bevel (37 1/2 per side),
1/8" gap +- 1/32", 1/8" land +- 1/32".