Upgrading to High Sierra

I'm going to attempt to upgrade to High Sierra later tonight. I do not have another SSD to do a CarbonCopyCloner on in case things go wrong, however I keep regular time machine backups and I have my home folder (with basically everything in it) on another 2TB drive.

According to TonyMac, the upgrade should be easy. Just hit the button and go for it, then update Nvidia drivers. My 750Ti isn't going to need anything upgraded.

The only issue there is audio, which it says will break. I have a Gigabyte z97n-wifi, which uses Realtek ALC892. What do I need to do to fix the audio after upgrading?

When I built the box in the early days of Sierra, I did use the Multibeast tool (cue the hate). I had, however, used createinstallmedia for my installer boot usb. I have not updated clover since, so it's probably still a 3xxx version. Should I update this before installing?

Then there's APFS. I've got no problem with it, but I believe I'll need apfs.kext before I install. How do I get it, and where do I put it?

Am I missing anything? Hopefully all goes well. Will create a Sierra installer USB again before the upgrade to I can reinstall Sierra if it goes south.