I think this sounds like a great idea! Etiquette can vary so much depending on where you are, and a major etiquette error could potentially offend your clients, or even cost a company business.
I've traveled in Europe, although not extensively, and I found that a lot of the travel guide books will have sections about this very topic, as well as information cultural expectations and practices in that country. I've used the Eyewitness Travel Guides, and, IIRC, there is also a series called 'Let's Go!', and both were great. I'm sure you could find them at a local library if you needed some information. Oh, and all of the other ideas suggested - awesome!