Chromium

As I've been creating my own parts, I've ended up going the "scale collision meshes to 99%" route, which I prefer to allowCollision 0 to avoid having rockets with (intentionally or accidentally) intersecting parts. Looking forward to seeing someone more experienced answer the other questions, though.

Very nice models, well-suited to use with Orbital Construction. Great work!

That. Is. Awesome. I would LOVE shirts with that on it. That's really all there is to say on the matter.

Your problem there is the G. Capital, or 'big' G is the gravitational constant, equal to about 6.67 x 10^-11 m^3 kg^-1 s^-2 (don't mind the wacky units, that just makes equations balance). Lower-case, or 'little' g is the acceleration due to gravity on Earth's surface, which is 9.8 m s^-2. You want to use Big G in this case. Also, remember to always calculate r as the sum of your altitude and the planet's radius. For a 100 kilometer orbit, the r in your equation is actually equal to 700, which is your altitude plus the 600 km radius of Kearth. We do that correction to account for the fact that you orbit the center of gravitational attraction of a body, which lies at the center of a planet.

Blender's COLLADA support is years out of date at this point. Sadly, OBJ is really the only option for Blender users.