1. The motherboard supports UEFI, but Windows was installed with BIOS emulation. We needed to install Linux in BIOS mode as well to get a compatible partitioning scheme, but the USB device we were using booted in EFI mode by default (for those distros that supported it). Using the F12 boot device menu on boot allowed us to select to boot the USB device in non-EFI mode.
2. Only some of the USB ports seemed to work for booting from USB or for use in linux once booted. We saw errors like:
Enabling the "IOMMU Controller" option in the motherboard configuration fixed this.
usb 3-1: device descriptor read/64, error -32
3. The built in ethernet device appeared to be available, but refused to connect to any network. the IOMMU Controller option fixed this too.