I have a probe in the tank, so I see the pH all the time. pH is pretty steady at 7.8-7.9. Granted I don't know what the pH SHOULD be for YWG larvae, but that seems like a pretty safe range?
One of the bigger, more developed one has his pelvic fins now, and more black spots along the tail, some different sizes (like the ones you see in the day 13 side view above.) Everyone should have their pectoral fins now.
I have not seen any settling except for the one night that I mentioned above, but it's a bit early for that.