The second and third logos are my personal favorites. I like the way you incorporated the school book into the door of the barn for both designs, though I feel like the third one feels a little less cozy...
Yes it's a 3D application that came out around the same time Character Studio Max came out... I'm not sure on it's relevant usability in the industry now a days but I'd start learning Maya if I were you... every company is starting to turn towards Maya. Great for game platforms and Visual Effects.
I'm pretty sure Rhino was just intended as a modeling program for an alternative to using Lightwave's and 3d Max's modeler programs (it could export to tons of different programs for surfacing and animation, not sure on import though). I always heard it was a pretty decent modeling interface though some people liked it better and some didn't.
I still think modeling in Maya is a pain in the rear though.