Gee, this sounds familiar!

My DD (who is now 13) used to have the exact same problem with table manners, lol. We solved it by tackling one issue at a time-first the open-mouthed chewing (gross!), then the clacking silverware, and so on. Every time she got something right, we would reward her; when she finally made it through a meal with no serious flubs, we took her to a friend's Chinese resturant after hours and let her have full run of the place, lol.

I don't recommend rewarding your daughter with food-it sounds like that might be a bad idea-but maybe something like a small toy or trip to the park would work? You have to get your husband on board, though. Tell him that bad manners will hold her back socially and professionally for the rest of her life or something. If you can't get him to help, set aside time when he's not around to teach her. He may be one of those guys who sees good manners as a form of snobbery or something, lol.

Good luck!