So, I'm about half way through my schematic, it's tough with the amount of free time I get but it's coming along.

Giving Altium CircuitMaker a go, normally I'd use Eagle but I figure I'm so far out of practice it doesn't make much difference either way.

Have decided to compromise, in order to be lazy and keep using ATmega32u4 - Mostly for the simplicity of built in USB - frame buffering will be done on the host and streamed via the MCU to the EPD.

I could render the frame for a 2 inch EPD on the MCU but it uses 2.4k out of the 2.5k of memory so it's just going to be easier this way - it'll be faster than relying on external flash and a lot simpler than picking a bigger MCU and working out USB.