Can we drive this into the ground? You betcha.
Breaking and entering is not analogous to spelling and grammar. Just because two separate (but equal?) nouns are almost always used together does not make them a singular compound. Breaking and entering is a compound of separate nouns to create a new singular noun. You need both to create the specific noun you are referring to, while spelling and grammar are often combined under one banner but remain separate, just as a library may combine books about "Penguins and Chassidim" under one category even though they remain entirely separate, or a college course could be about "Language and Pedantry".
1) FTFY
2) You make a valid point, although I still think it's defensible. I'll advance one possibility: In the comment, I could have been referring to the "Spelling and Grammar" of the course offered by my college, although perhaps "spelling" and "grammar" should then have been capitalized 😂 . Additionally, I believe that spelling and grammar have been lumped together in common use often enough to become one unit.
3) For one with such command of the English language, this is surprising. The structure of your last sentence is both incorrect and incomprehensible, which could (ironically) have been remedied with an additional comma instead of a period following "referring to". Unless this was a "spell-check" moment? (Notice how the common usage of the word spell-check denotes checking both spelling AND grammar. Another point for me.)
Your apology came at the end of the post, not in advance. Granting you an Oxford Comma, I count four superfluous commas and one superfluous em dash.
1) I meant in advance of the accusations that were sure to fly, and you promptly proved my word prophetic.
2) Please name which commas were superfluous. You can reply by posting the sentence without the superfluous commas and we'll see if it's true. I'm withholding judgement for now.