Not so much a crossword, more an assault course. Have enjoyed and completed many Maskarades in recent years but this left me floundering. Finally get it with your help but really . . .
Nelliegee, Lear is not one of the kings. In 67a, bridge opponents at the start, symbol in the middle, one letter abbreviations for king (Latin and chess) at the end
In 38d, symbol is at the end. It reversed in a word for fresh as in not long ago
M, interesting, I have the curved line, though I know it from musical scores rather than typography. The equals sign interpretation hadn’t occurred to me.