My course is a graduate computer science course, but one of my goals is to explore Lua as a possible working language for a revision of our core undergraduate course on Programming Language Organization in 2014.
An excellent plan, I've always felt that Lua was a good fit for an educational language. I believe there have been some courses operating in Brazillian universities, so there is experience to tap into.
You mention the difficulty of finding out 'best practices' for Lua. Again, PiL is an exemplary text book. The important thing is to have a corpus of good code for reading and imitating (which could be itself a subject of another thread).
The Wiki has some really good stuff in it, but I guess it needs a 'recommended reading' page, wikis being what they are. I think the coverage of functional topics is particularly good, if scattered.
I've highlighted some issues in the Unofficial Lua Faq (uFAQ)