I'm afraid this might be one-a-them...
memes, or somethin'.
Does it matter?
A. . . . For example, I might talk about my mother's brother Ned, as opposed to my father's sister, Susie. Why the comma in Susie's case? Because my father has only one sister, whereas my mother has two brothers, so we need to specify which brother but do not need to specify which sister: we do not use commas to separate the name from the rest of the sentence if the name is essential information—"restrictive," they call it. Susie's son, Jonathan, is my cousin, and we set his name apart because Susie has only one son, so if we left out the name "Jonathan," the sentence would still make sense: the name is additional information, not information necessary in order to know which son we're talking about. Ned's son Ted—and Ted's brother, Pete—are also my cousins. (Ned has two sons. Ted has one brother.)
So, similarly, you'd talk about "Jesus' disciple Mark" but "Batman's sidekick, Robin."*
A. You noticed that, did you? Yes, usually I don't make names possessive by adding only an apostrophe (as opposed to an -'s): I would refer, for example, to "Ritchie Valens's death." We get taught that words ending in S are made possessive by adding only an apostrophe; this in fact is true only for plural words ending in S (e.g., "dragons' livers can cure colds"). The exceptions are biblical and classical names like Achilles and Moses, which is why I did write Jesus'.
I used to teach my students that the apostrophe-without-an-S option was acceptable since it was so common, but—and this is key—only if you aren't pronouncing the S. For example, Denis Johnson's title Jesus' Son† is a three-syllable affair. This works both ways: if you pronounce the possessive in "Edwards's candidacy" as Ed-wurd-zis, then you need to use the full -'s; if you pronounce it Ed-wurdz, leave out the S. There is no silent S, nor is there an invisible one.
A. Yeah, no, it's "less than 20 minutes," not fewer. Same with money: "less than $10." What made you think of that?
A. Because you're not really saying "how many minutes" or "how many dollars": you're saying "how much time" and "how much money." I feel like we've been over this before.
A. OK, we have time for one last question.
A. Yeah, with or, the verb agrees with the closest subject. So, like, the dog or the cats have been shedding on the pillow, but the cats or the dog has been peeing on the rug. This results in wackiness when you say something like, "Either 100,000 sand fleas or one octopus is going to be the main course." But don't eat octopus. Monkey Einstein, remember?
* DC comic-book fans: if Batman has in fact had other sidekicks, go ahead and keep that to yourselves, OK?
† Not set apart by commas because Denis Johnson has more than one title.