Regarding the size of the pot, this is a link to an article by Brent Watson that explains why over-potting (using a pot that is too big) will slow down the growth of the tree. He has some other excellent articles on the site as well about using the natural cycles of the trees to the best advantage for developing your bonsai.
www.evergreengardenworks.com/earthpot.htm
That was a good read. Thank you!
