When you're not actively preparing, eating or guarding your food it should be locked in the metal bear boxes available at each campground in Yosemite National Park. Nothing, not even a water bottle or a candy wrapper, nor anything that a bear might mistake for something hiding food, such as a child car seat or a blanket, should be left in view inside your vehicle, and nothing that might have an odor such as an ice chest or garbage should be left in the trunk of your car. Doing so will invite bears to break your windows or jump up and down on your vehicle, and in addition you can be ticketed by park rangers. You should've already been warned when you made your reservations, but upon entering the park and entering the campground I'm sure you'll be told, given warning pamphlets and see signs explaining the rules. Remember that any bear that breaks into cars or raids campsites will almost inevitably have to be killed.
As for your other question, almost any food you eat at home can be taken camping. Most people have coolers they can fill with ice or dry ice, hot dogs, chicken wings, ground beef, cheese, eggs, milk, vegetables, fresh fruits, etc. and the campground bear boxes should be big enough to hold a large one. Besides that any canned foods, dry mixes, breads, etc. will be just fine. You're only limited by your tastes and culinary skills. Planning, purchasing, packing, and preparing the meals for a camping trip is a job unto itself and no one person should have to do it all. Get your family or group together and plan it together, budget, and make sure everyone will have something they like, something you'll be able to cook on a campfire or camp stove, and will be nutritious and provide energy for outdoor activities.
If you're planning hikes, horse-back rides, bike rides, tours, etc. you'll want to bring foods you can fix in the morning to carry with you for the day including lunch, snacks and ample liquids, such as sandwiches, trail mix, Peanut M&Ms, and Gatorade.