I've noticed some patterns but I've never really been told any specific rules for if or when it is pronounced (except for that general rule that it's silent or it might be a glottal stop or theoretically some other weird pharyngal/glottal (?) sound). So I guess still the only thing it does is testing my nerves :)
Pretty much. My understanding is in certain populations (Yemenites is a group I've heard mentioned) they do pronounce ayin and aleph differently and traditionally that was the case. I know an Israeli- American (bummed we're no longer in touch because I'd love to ask him more on this) who despite being originally from Bulgaria, I think it was, and growing up on a kibbutz pronounces ayin and makes the argument it's pronounced differently than aleph. But he's also aware that's not the general present day pronunciation. His wife is a rabbi and does a lot of Jewish education stuff and basic Hebrew lessons and I remember them debating this sort of amongst themselves (and flowing back and forth between Hebrew and English as they do, so not the easiest to follow!) So not exactly helpful but yeah, certain subsets in Israel have different pronunciations but they're in a minority for sure. The guy I knew definitely spoke with more glottal stops than most, so I think that was how he used ayin? It was near impossible to teach which is perhaps the reason it's fallen out of use. It sounds interesting though, for sure.
Also with you that I'm regularly confusing spellings because of it as well.
If you listen to the Arabic letter ع (also called Ayin), that is what the Hebrew letter ע probably sounded like in biblical times.
Here's a clip of a Yemenite Torah recitation - it's positively gorgeous and you can somewhat hear the different pronunciation of the ע as well as differences in vowels: https://www.youtube.com/watch?v=lzOVNoSl6RM
Well, מִי and מַה are treated differenty. מַה can ask both for a subject and an object: מַה זֶּה what is this? and מָה אַתָּה רוֹאֶה what do you see?. But מִי can only ask for subjects: מִי אַתָּה who are you?, but needs the object marker, if asking for an object: אֶת מִי אַתָּה רוֹאֶה whom do you see? If it is used as a relative pronoun like here, the same rule applies. By the way, traditional English makes the same difference between who and whom, but has only one form for what.
Actually it would mean "They know what we are not". For example, we led them to think we are chefs, but after they tasted our plates - they still don't know us and don't know what we are, but they know what we are not (chefs).
Of course, that's quite a sophisticated, even smart**s sentence; the direct answer Sheila is "no".