I just found out that Colnagonews.com has a nice collection of the geometries of the bikes that they have built over the years for different famous riders. My question is, where are the basic stats such as STA and HTA? Are they fixed for all Colnagos? Are the small numbers (usually in the teens) near the seat tube cluster the setback from the BB to the top of the seat tube? What about the HTA?

Here's an example of the chart for Beppe Sarroni:

http://www.colnagonews.com/prova2/storia/geometrie/beppesaronni.php

And Eddy Merckx fiddled with his design basically all the time:

http://www.colnagonews.com/prova2/storia/geometrie/merckx.php

Thanks in advance for explaining this.

They basically only care about seat stay length, front to center, TT length, set-back, BB height. The angles will then fall in whatever place it's necessary to achieve those lengths. It's just a different way to look at things and I think it's easier to build using this method as well. Measuring angles would require much more effort and increase the risk of errors.