To my knowledge, the piece initially came with baton markers and (approx. mid-90s) also with the roman numerals. I guess that's what they might have called 1st and 2nd series. 3rd series is probably the last run in the early 2000s where Patek decided to build some more pieces. These have a different movement thought and are less interesting for a collector, if you ask me. They did some special dials then, though (including the Breguet dial you mention).
Based on my research (primarily based on how often pieces have shown up over the years at major auction houses) the J-Baton version was produced in the greatest number by far (I would expect approx. 550 pieces). All other metals of the Baton version seem very rare (maybe less than 200 in P, even less than 100 in G or R). Of the Roman version there were less than 150 in each metal.
In total, this would result in about 900 made with Baton markers, and 600 with Roman. That is, "First" and "Second" series total should be around 1500 pieces. Not much. And the 5050 was a milestone in Patek's corporate history as it was the first retrograde perpetual calendar produced as a series.