A:AnswerYes this lens will work perfectly fine on your 80D, but........
you will have to take into account that you are using a lens made for a full frame sensor and the 80D is a crop sensor camera. So the 70-200mm range you are expecting will be more of a 112-320mm instead. Hope this helps.
A:AnswerCanon Rebel models are compatible with all Canon EF and EF-S lenses. Make sure your mount has a red dot for EF lenses and/or a white dot for EF-S lenses.
A:AnswerIt should be compatible. Make sure your mount (metal ring) has a red dot; if it does then take the lens red dot and match it and turn and lock it in.