Lots of different questions here. Volunteers are not considered donors in that they can't really deduct their volunteer-related expenses as donations. Nor can the entity claim them as revenue, unless the volunteers donate to the nonprofit and then the nonprofit buys their tickets. In general,...
My first startup was exactly in this space. We topped out at $500K/year before the 2009 recession trashed our client roster. I'd be happy to discuss what worked for us.
The key skill sets are determined by whom you are targeting for training. Customer acquisition channels will also be determined by whom you are targeting.