Kim,
Good point on the quality of the switches. I'm planning to use a reasonably good make (Crabtree), and I could probably withstand a few failures as they're easy enough to change out - no need to isolate mains power, as there won't be any. Sounds like using a small pre-installation test rig's a good idea, catch the baddies.
Could you elaborate on the diode and load resistor - how do these get wired in, what do they do?
Thanks,
Ian