Sounds tough. First off I highly recommend Love and Logic so it's good you're already reading it. I personally think it's the best.
Second, I get what you're saying about not rewarding her for a bad day, but you also don't want to pile on so many punishments that she doesn't ever see a light at the end. Sometimes you need to just let there be a consequence at school for school things at home for home things. So if she has a bad day at school, talk to her about it, brainstorm ways to make it better, maybe make her practice "the right way" but don't necessarily take away all her at home privelages.
As far as the food thing, I think it's fine that you threw away the fruit, make sense but just be careful battling over food, it's not so much worth it! If she has healthy choices in front of her and only wants fruit for dinner then it's probably fine. I know she needs protein and other things but sometimes you have to let them make their own choices on some stuff and if it's healthy and you're offering it then let it go.
As far a sticker chart or whatever, well in a way it's bribery but sometimes we have to motivate kids extrinsictly before then have the intrinsic desire to do it for themselves. So it might be worth a shot. Start with small rewards like an extra TV show or 20 minutes of additional outdoor playtime or game time with mom, etc. and see how it goes.