I love your quilt! Gorgeous!
As for your question, looking at the tutorial that was posted by K3N (
http://www.quiltingboard.com/t-36303-1.htm) my guess would be that you could either make the batting for the outer blocks larger (cos you'll need more batting on the outer edge to accomodate the binding)or you could join strips of batting to make up more than the size of your binding and cut it down to size?
I think thickness of binding will be dependant on your preference. I love your quilt as it is but a thicker binding will still look nice. Hope this helps. I am sure that there are more experienced quilters out there who probably have a different way of doing things.
Have fun!