I would like to use my Sigma 600 Mirror lense on Nikon M80 digital camara body lense was used on a Pentax Super A camara before can it fit

SOURCE: sigma 28 80 mm mini zoom macro

No se como un lente puede romper el anclaje al cuerpo de la camara, pero si en verdad se rompio, deberia llevarla a una tienda fotografica para que la arreglen. Le queda tiempe en la garantia?

SOURCE: Sigma 170-500mm lens - anybody know where I can find user manual

Check the Sigma site. They have the specs for the APO lenses.

SOURCE: Can I buy an adapter to use the 28-200 mm Sigma

You may be able to find an adaptor, but I doubt it and you would lose many functions in any case. It could end up that the lens will not auto focus or that it would not meter properly. These adaptors are made so that specialty lenses (such as fisheye or shift lenses) can be mounted on cameras when needed. Your 28-200 would probably be cheaper to by in an EOS mount.

SOURCE: Currently I have a Nikon F65 non-digital camera

If anything, you will gain image quality because the sensor on the D5000 is smaller than a frame of 35mm film. Thus you will only be using the central portion of the lens. On the D5000, the 28-80mm lens will act as a 42-120mm would on the F65.

However, you will lose autofocus capability. The D5000 does not have a focus motor in the body, relying on the lens having the motor, and neither version of the 28-80mm lens has a focus motor. The lowest-end Nikon dSLR with a focus motor is the D90.