3 gallon pots are primo.

Wait for it to get pretty dry and tap on the pot. You want it to all come out in one piece. If the dirt looks like it's going to seperate, don't do it and wait for it to get dryer. If you can, you could also just the bottom out of the smaller pot and make a hole about the size of the pot in the bigger, and there you go. The roots will find their way.

Window light isn't the right amount of light it needs. Buy some cfl's, you got some stretching. Put in the cfl's and you should be alright.