Good tips.
We also noticed the problem and came to similar conclusions. Have you had the chance to test your ideas? Did they work?
Something that we also thought about (but did not implement yet) was to hold regular introductory workshops for beginners.
We also have many people that subscribe to the meetup group, but come only a couple of times and never again... (do you also?)
I think that it is somehow an inherent "problem" (feature ;-) of Scala, that being it so broad inevitably you have people doing very advanced / esoteric stuff and others barely starting.
Cheers,
Sebastian