Bill;
Not up enough on the NID's to answer your other questions, but; there was an overlap in production of the Flues & NID, but not in SN's. The 425,000 SN was set far enough ahead to eliminate the Flues #'s. As I recall they never reached 400,000. The pins you mention would be the cocking indicators. I believe the Star is simply a variant found on field grades but others can give you better info on this than I. If in good condition will make a good solid shooter.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra