If my opponent is using E-Heros, and they play either poly. or miracle fusion, would fairy's hand mirror, allow me to choose different monsters? and i so and the poly used any from their hands could i look at their hand to reselect, since they're selecting specific monsters?

No, because as I recall Fairy Hand Mirror only works on a card that specifically designates 1 monster, and on the field. It would only work on stuff like Soul Exchange, Brain Control, Equips (- Premature) etc. And just for future refence, this PROBABLY should go in the Rules forum.

A.) This should go in Rules of Dueling

B.) No, it does not work because no monster on the field is being targeted for anything...