59.94 MHz to be precise, which is what I mean when I say 60. It’s standard for LCDs. Guess I shouldn’t have said “exactly 60” above.
Also the reason that those setups use 768p is because 720p native monitors are incredibly rare and hard to find as they haven’t been in production for years. I do have one, but it’s from 2006 which is actually the most recent model I was able to find (Gateway FPD1775W). 1366x768 monitors are in abundance though, so those are used. The games are all still output at 720p (or 1280x720) though - the monitors just scale them up to fit their 768p / 900p / etc resolution.
This part remains a mystery to me too. I only know that all 720p games have this, but I don’t exactly know why. My best guess is that it has to do with some kind of hardware limitation in outputting a 1280x720 image.