I think this sounds like a great idea, Emily!  The only thing I'd think about is the community talent night being focused on beginners.  I find that experienced contra callers and bands are often better for beginners because callers who've been doing this for a while are usually good at seeing when the call needs to be supporting new dancers, etc.  Similarly, experienced bands I often find it easier to find the count of the music- sometimes when I'm hearing musicians who are not used to playing for contra, it can be difficult to find the 1 in their phrasing...