Truck/car camping can provide you with the most creature comforts because of the weight factor. I too have a problem getting the family into the woods. So, good for you that you are at least getting them out there!
My advice on food is just echoing what has been said. Good coolers, lots of ice, use tupperware and ziplocs for everything. Keep it out of the sun, under the shade of a table or tailgate. One thing I also like doing for the first night, take some frozen steaks and put them in the cooler just as you leave. Pack them in tight in the bottom and by the time you are ready for the first nights dinner, you can treat yourself to a nice campfire steak. Hotdogs, especially with kids, are a staple for me.
So far as keeping wildlife out of it, will put my cooler and dry boxes back in the bed of the truck w/ the tonneau cover down. This will keep the "critter" type animals out of it for the most part. If bears are a problem, in most State and Federal campsites, they have bear boxes to stow stuff in. I would not lock it in the car, bears will break glass to get in.
Organization is also a key in my camping. Everything has a place, everything goes back in that spot. I use big Rubbermaid containers with the lids that overlap the edge...and the lid is snapped on at the handle. These tend to shed off the rain and everythng stays dry, unlike the containers that have te folding hinged lids. Also, when I truck camp, I keep my clothes in the vehicle too, for the same reason. There is nothing worse than wet soggy gear after a sudden rain. My mindset is that rain is always 30 min away so I never have to scramble if that comes up.
Dirt in the tent is inevitable. I try to stay out of the tent until I go to bed. In and out all day long for no real purpose just ends up getting sand in your sleeping bags. Keep the tent door zipped up, and the rain fly on.
Take lots of games. I like dice and card games b/c they are easy to pack and don't usually blow away (like Monopoly money

). A frisbee and football can break up the afternoon. Fishing is always on my list too. I keep a seperate cooler w/ blue ice for worms.