If I drop off one of the fans will he/she get e-mail that I am no longer a fan of him/her?

Nope, but their fan number will go down.

No, you only get messages when someone fans you.

Their number will go down, but depending on how many fans the person has and how often they're added by people, they probably won't notice if you drop them.

link

the number will just go down like once someone faned me and didn't mean to so she unfaned me and it just went down : )