Allright, what on earth is the right spelling of this?

Anyway, I have a tiny ginkgo in a pot. I bought it as a 6-inch seedling and it doubled in size over two seasons. This seems a bit fast, doesn't it?

At this time, it is a single stick with leaves on it and I can't see any sign of branching. Should this plant be topped to encourage branching? I worry that I'll end up with a tall skinny stick in the end.

I keep it over the winter in a greenhouse. Since it heats up early in the spring, this little tree is growing faster than my friend's (she bought one from the same batch but keeps it outside all the time - she sinks the pot into the ground over the winter). Which is the better way?

Can anyone give me some pointers or web sites where I can learn how to properly start to bonsai this little guy. It's become a bit of a pet :)

Chris