First of all, what you carry on your back, whether you're on a day hike or backpacking become a matter of individual preference. I've seen experienced hikers go on long hikes with nothing more than a few bandaids and a small bottle of water. I've also seen people go on fairly short day hikes with large packs to cover multiple contingencies. In both cases it's what your comfort level is. Just think safety at all times!
You can save money by using most of the same equipment both for backpacking and camping but you'll sacrifice some level of comfort by not bringing heavier equpment car camping that will provide more luxury such as a larger tent, larger sleeping pad or cot, larger variety of cooking equipment, etc.
As far as wind and rain protection a good tent with a rain fly should be all you need. Try to "leave no trace" of your visit by leaving everthing as you find it and not using wood for structures, fires, etc.