Make no apology! In fact, thanks for taking the trouble to pen such a detailed reply - it really does help.
From my own point of view, I started by collecting the date run 1860-1956. Having done that, obviously I needed a 1860 beaded border as it's quite different to the toothed and to my mind, clearly a different coin. Heaton mint marks? Of course - they're still clearly different. Large 9? Hmmm... Close sixes? Maybe... And so it goes on.
Personally, I don't much like my 1862. The imperfections to the C and T, and lack of a second stop in the colon detract from the coin. It means I need a better one with all the detail intact. Each to their own, of course, but it is difficult to know where to draw the line, and I haven't quite decided yet either.
As for reverses C&D - I'll let you know when I get there. I've only got as far as 1866. Flippin' USB microscope - now I've got to examine every letter and every number of every coin. It makes everything look worse - look at the state of the date in what I previously thought was a half decent 1860BB - I need a new one of those now!