You can mount m43 lenses on it with a fairly small adapter. And the wide kit lens is pretty darn small. I've also carried the nex5 with the 18-55 mounted in a jacket pocket that I definitely couldn't have carried a dslr in.
I just don't think there will exist a program that does exactly what you want, so you either pay to have it written, or you just have a group calendar, which google apps does just fine.