Hi Mike,
I'll kick it off...
Part 1, I sadly have no idea, but these silver/nickel badges seem to be very rare, and I am not convinced they formed part of the OWS set. That said, they could have been made for a very small select group, hence the rarity. I also think Tony is referring to the 1914 enamelled badges, as far as I am aware, they have always been referred to as "Admiralty" badges. Be interesting to see if anyone had better info there.
Part 2: I think the enamel has just been removed, the spaces around the date seem to have some residual enamel, to my eyes, anyway. As for the raised B, from my observations, Collins badges (on the button hole fitting) come blank, stamped A and stamped B, along with the number, but not sure about the raised letter.... may need more opinions there...
On another note, I have very much enjoyed this thread, I have not contributed much, as I've been away, enjoying the mountains before we are put back in our box for the winter.... apparently France has another lockdown coming....
Cheers, Tim