Concerning lighter string gauge availability:
I seems to me that late in the 60's Ernie Ball came up with the idea of letting the players assemble their own set. What you would find in the store would be trays of individual sting gauges, starting with .008 and working up into the the low 60's. The display case gave you some idea of what gauges could be used in what positions, but you were basically free to pick and choose at will. You were essentially buying 6 strings rather than a set. Don't ask me the price. It was shortly after that I noticed complete sets of 8's, 9's, 10's, etc. D'Adario was one of my personal favorites.
