You can get a big "blotter" size calendar at Office Max or another store. Hang it up on nails and write different people's activities with different colors."3 Steps to a Strong Family" and "7 Habits of Highly Effective Families" have great ideas for organization in busy families.
About food: You can have your kids (because they are waaaaaay old enough to be doing chores and making household decisions under your direction and guidance) write up dinner menus with you. You can go to the free nutrition guidelines suggested by the gov't. and then the planning becomes educational because then they get to write down whatever they want for dinner, but they have to include enough variety for their health. When they make the plans then they "own" it, and they'll take pride in it and enjoy it. Plus you'll be helping them be proactive in choosing healthy foods and enjoy the blessings of planning ahead.
I think www.mealmixer.com has outstanding features. But you can check out dozens of kid-friendly cookbooks (for a jumpstart, not for every single thing you're going to make or you'll burnout) from the library for free. They can write down foods that they like on index cards and sort them into groups like entree, side veg, side fruit, grain, drink, and then have them put them together and see what they want to combine for taste and appearance....and they're things that you already know your kids like, so you can introduce new things to them if you want to in addition to what you know they'll eat and be healthy eating. Probably one of the easiest way to come up with a successful menu. You can post the cards on the fridge in order so you know what's on the menu for the week. I also recommend www.flylady.com for free ideas and support.