I'll keep it short and simple. I don't want to rain on your parade but, commercially, I think maintaining SANOS is a waste of time.
The landscape is littered with the corpses of FOSS projects that were a good idea but turned out to be unnecessary or never gathered enough support. You may get a small cadre of people working on a project like this but to what end. Where are the installed bases for BeOS, Haiku, ReactOS et al?
Let's be clear. Linux is so far ahead in terms of development effort that those other projects would take decades of effort just to catch up. I'm not talking about technical merit here (although that may be the case as well) but penetration into the mindsets of business. And business is, unfortunately, where the money comes from.
Those four bullet items you list are already available in Linux so what would be gained by adding them to another operating system - people can just use Linux.
To answer your specific questions (be aware that much of this answer is my opinion - my wife will be happy to tell you, frequently and without much prompting, that I've been wrong before -:)
1. Does anyone here have experiences they would like to share using SANOS?
No, I'd never actually heard of it until this question popped up on SO (which should go a little towards justifying my statements that it will likely never be important in the grand scheme of things).
2. What is the most expedient way to attract others who would like to contribute time to make it better?
This is a good start since you've made a large community of geeks aware of it. I'd shop it around some more, you need to get the size of that cadre up.
3. In what ways is it better than either the kernel used in BSD and/or Linux?
No idea. I have zero interest in this project since I'm more concerned with running a business and spending time with the family than donating my time for free to a project that I think will go nowhere (I'm not trying to be obnoxious or condescending there, that's my actual belief). Given it's minimalist approach, it's possible that it could be faster.
4. Is there merit in porting Ruby to this platform?
Other than as an exercise in porting, probably not. The Ruby crowd are not going to swarm across to SANOS just because you make it available. They have to earn a living as well.