Here's the Lua words spreadsheet with some additions and corrections - i want to make it more of a single reference for Lua programming on the camera. It's still far from complete but getting there.
I've found the chdkcam version of chdk invaluable to control the camera and run snippets of Lua code over the USB link. No more memory card swapping. Shame it's not available for all cameras.
If anyone wants to add or fix stuff, feel free to repost with an updated version of the spreadsheet. Keep the descriptions short but enough to be useful. e.g. include value ranges, return types etc.