I am getting the Nexstar select for xmas this year and I have a question about the Realflight sim. Does the transmitter have to have the batteries or is it powered from the usb port? This may be a dumb question but I'm asking anyway. Also, how close is the sim physics to the actual physics of the Nexstar in flight?

The transmitter that comes with the Nexstar select has NiCd batteries and the radio needs to be on when using sim. For longer sim time you can remove the crystal which some believe should be done anyway.
The sim physics are close they helped me quite a bit with my Nexstar. The plane in the sim can roll better than the real thing and seems more powerful in the sim. When you do fly the real Nexstar I recomend a club with some instruction. Also don't use the AFS that is on the plane. You'll learn much faaster when your in control.
Jim

If you use the AFS, make sure the sun is directly over head, or the plane will head for the sun, and is very difficult to get to return.