Those are a lot of questions, and I am not certain how to answer, but I will try.
About the aerial: I do not know exactly who did the referencing, however what this was was a contracted flight to create pictometry, each section therefore has 5 views: birdseye (which I am using) and north, south, east, and west obliques. I acquired it from our county, who oversaw the process. They use the coordinate system, so I am assuming that that was how it was delivered, but I could be wrong.
Direction is not consistent, however this is based on the few valve locations which are visible in the photo (steel lids are hard to pick up from asphalt) I do not have any other solid locations to check against yet, but could go grab GPS points for the sewer manhole lids which show up pretty well. As to resolution, I can measure, in arcmap, the diameter of the water valve boxes in the areas where they show with decent contrast, and they are right about 1 foot in diameter.
You lost me with RMSE and the other parts of your question about the imagery.