All of the old data sheets and formations are aparently done and in the Pandorax book that came with the collectors edition. So we will have to wait for it to be released at a later date (I'm sure
GW confirmed it was coming). The general feel I get from online is that old sheets are viable and formations are free to use, but if they refere to an asset or rule that no longer exists it's ignored. As with all
FW and
GW stuff if there is a newer version of the rules/data sheet it makes the old one null and void. It's annoyed the shit out of me as I can't use any of my Tau stuff untill I get the second edition Tarros campaign book... I was hoping the units would be in the Apoc book!