Hi again Tailwag,
The term piggyback implies just that. The camera with its own lense rides piggyback style on top of your telescope/mount which is tracking the stars. The telescope is not used in the image just a platform to track the stars..
For a good beginners scope I would go with a ED80 like one of skywatcher/orion/saxon 80mm ED scopes or a william optics 80 or 90mm APO if you have some cash saved, mounted on a Heq5 or better yet a vixen sphinx mount. There is soo many choices out there to start you off. So this is only my opinon..
Oh by the way you will need a remote/timer for your camera to do "bulb" exposures (longer than 30sec) will cost you around $50 from any camera store. Like cometcatcher says you can get some nice pics with just a standard tripod 30 seconds at a fast iso..Just focus on something on in the distance or in the twilight then switch the lense from AF to MF before shooting. (on the lense barrel.)
Cheers Gary