i would try not to make a big deal of it, or label her. kids can get annorexic so young these days...you can not control her eating - that is what she is trying to do, its not about you at all. dont make food a reward. dont make food an issue (as hard as it is!).
stop sending her to her room for not eating, but id say for whinging is ok. maybe if she is hungry after her meal she can have 1 slice of bread or one piece of fruit? a glass of milk? might stop the whining..aslong as she does eat good food when she does eat she will be fine, even if she skips your wonderful dinner then has the good food afterwards) she will eventually grow out of ignoring family meal times if no attention is paid as humans are naturally 'sociable'.
i like the idea of getting her to help you. can she help decide the menu? HELP YOU COOK?
THE ASSEMBLE YOUR OWN MEALS IS A GREAT IDEA (oops caps sorry) - homemade pizza is another..
the buffet/load your own plate is also great...especially if its a social occasion like a party, BBQ, friends/family over for dinner, or a special visit to an all you can eat buffet.she needs to realise (on her own) that her choice of food is yummy and fun. sometimes kids eat more at their friends houses than at home? they try new things
can you ask the school to do a cooking lesson, where the whole class helps to make something (say fried rice for example - or another country's food as part of a study about that country??)
goodluck with it


ETA-- i do not like the reward ideaLOL