Hi Mike,
ah, glad to hear somebody else is experiencing it too! 
The slight shift in numbers when adding CPs is normal though, since with every new image RC gets new information and the calculation is adjusted. You can observe those changes in the 3D view. When you start out with 2 images, the CP might be quite off, especially if the two images are close. Adding a 3rd one, preferably at about 90° to the first ones, the accuracy goes up and the CP shifts to the new position.
Where did you get the PP from? My screenshot?
Yes, those are ground control points measured with a total station. In German surveilling it’s called a P ■■■ p unkt. It’s actually really simple, you just tell RC this CP is at exactly those coordinates. Then RC tries to make that fit, although only as much as it can. It will show you the remaining error, which is quite nifty because if it’s too big, it points to either a problem in the model or the surveying. I once discovered a fault in one of my PPs because RC would not shift it where I wanted it to be. Since then, I trust RC in terms of accuracy very much… 