Hi Jeff,
I'm just getting started building a Cozy myself, so some more experienced folks may be able to chime in and expand / correct me, but:
1: A Cozy 3 was built 10% enlarged (http://www.aircraftspruce.com/catalog/kitspages/dbutler.php). This will likely add a lot of time and complxity to the build, however. I am building a wider fuselage, and there are a LOT of domino-effect changes that come with it. Personally, I don't mind.
2: Velocity has been around for a long time, and I'm not aware of anything that would suggest they will not continue. Indeed, they are continuing development (Velocity Twin for example).
3: As i understand it, it is a matter of wher the centre of gravity is in relation to the main gear when unloaded. For Cozy's, it's too close to let it sit on all-3 usually.
4: I recommend getting a small fibreglass practice kit of some sort, and playing around with the materials. Find out if you like it or not. I did, and really enjoyed it, so I'm building in composite! Some people can't stand working with resins etc., so it would would be a poor choice for them, obviously.
Hope that helps a little!