Apples are not real good candidates for bonsai. Crabapples on the other hand make real nice bonsai. Your typical orange does not make a good bonsai either. I have a few Fortunella Hindsii which is very simular and they make good bonsai. There is a tree called a Calamondin that will make a good bonsai. The crabapples will not do well indoors while the other two will. I am a regular at a site www.bonsaitalk.com It is one of the best for bonsai.
For all intents and purposes you can grow tropicals inside, but not most other types of trees. One of the guys that knows more about tropicals in the u.s. also has a website. http://www.bonsaihunk.us/