In order to quickly search for topics of interest, I would suggest that you get the electronic version of the CP's (CP#1-CP#82) from Mark Zeitlin's Cozy site at:
http://www.cozybuilders.org/ref_info/The first mention of the Long-EZ is CP#21, and CP#23 contains the first real info about the Long-EZ plans. CP #82 says that CP #24 and beyond are required to build a Long-EZ. I don't believe that you need any CP beyond the last realily available issue, #82; however, the Central States newsletters contain a wealth of additional information published since CP #82.