As far as I know, motherboard vendors just package the microcode update that Intel sends them. They recently claimed that they produced updated firmware for 90% of their models from the last five years, so you might see one for your soon(ish).
Maybe. I did come across a post on a third-party forum from someone claiming to have had feedback from Asus that their particular MB wouldn't be updated, and theirs was a generation newer than mine. But then this was just an anonymous post on an anonymous site so the usual pinch of salt applies.
The problem with the driver patch, as Morbad has pointed out, is that it loads too late in the boot sequence for Windows' built-in mitigations to see it, and activate. It provides protection down in the microcode (and fools Steve Gibson's checking tool) but OS-level efficiencies aren't enabled. Maybe Microsoft can be persuaded to leave their checking until later in the boot sequence but it seems unlikely.
Given enough time I'm sure people will come up with third-party edited BIOSes for popular mainboards, even if the manufacturer's don't. I'd have a go myself but I did kill a MB many years ago with a bad flash. There are better protections these days, but I'm still paranoid.
However, given that Intel can't seem to get it right even for their most recent models, what with random crashes happening (which they euphemistically termed "unexpected reboots") in the latest ones, you might want to wait a bit until it's better tested. (See what Zak Gordon wrote just above as well.)
Not had any issues so far, aside from the overcooking CPU mentioned further up the thread. And I'm more convinced than ever that it's the beta wrapper for the Asus utilities that is causing it with a bad sensor reading. I might try transferring sensor and fan control to the BIOS and foregoing the software altogether. The biggest problem with that is that the Asus utilities also control the mode of the 2A USB port that I use to charge an iPad. Not being able to switch that in software will be a pain, although it does default to 2A when the PC is sleeping so at least the tablet gets an overnight charge.
And, to be frank, you might want to think thrice before buying Intel again. Personally, I regretted buying an i7-7700K even before the Meltdown vulnerability was revealed, and afterwards, even more so.
Never had a problem with them, but Ryzen (Kyzen, whatever it's called now) was looking tempting a few weeks ago and even moreso now. Alas I can barely afford to upgrade a Happy Meal these days, so it's all very theoretical.