4. How do I get CORS data ?

CORS data are available on a file server at the National Geodetic Survey and since you are reading this FAQ you are probably here already.  To get the Data go here - http://www.ngs.noaa.gov/CORS/Data.html

You can also obtain customized data sets by going to User Friendly CORS at http://www.ngs.noaa.gov/cgi-cors/ufcors2.prl