I guess my issues with the instructions are dependent on how I got the image onto the SD card. Broadly speaking, if I download the ready-to-go img file it will behave as above (i.e. a bit wrong), otherwise if I start with a working distro/noobs and install the PiDP8 files it will behave the way described in Oscar's docs. Hence my confusion.
As an aside, I think I have narrowed my issues down to a combination of:
1. A bad solder joint on two switches
2. A faulty Raspberry Pi
3. A corrupt SD card (either cheap card, or not shutting down correctly, or both).
At the moment, everything is copacetic.