RE: CG Calculation Differences
Last year when I wanted to put together my own spreadsheet for Cg, I looked at a lot of different implementations. What I noticed was that there are a couple of effectiveness/efficiency coefficients buried in the equations that each author has used as his best guess. They tend to be slightly different between all of them and so you get different answers. If you go look up sources, you will get opinions of what they ought to be based on aircraft configurations, experience, theory, etc. So each author has chosen what he thinks fits model aircraft best.
I ended up using Adamone as my reference for crosschecks but they will all get you in the ballpark. After that, you have to fly and test.