Is USB Audio supported on the Apalis TK1

Is Audio over USB currently supported in the Linux build for the Apalis TK1 ?

Yes, looking at our default Apalis TK1 Linux kernel configuration it should very well be supported.

As a follow on question, can you tell me if audio over a USB BlueTooth dongle would work?

While it should depending on the BSP flavour used this may require further integration work (e.g. adding whatever required Bluetooth Linux kernel drivers as well as user space tools).