Regular walking actually builds up your joints. If your feet, knees, and hips don't complain, your present shoes, insoles, and socks are good enough.
I've been running more than 2000 miles per year for over four years now, and I feel better than at any other time in my life. I started running in steel toe safety shoes because that was what I had handy at the time, then bought a pair of real running shoes only after a few months.
If you eat a balanced diet, you should not need any supplements. That being said, many people take a multivitamin just to be sure.
You might want to check out the forums at
RunningAHEAD - Free online running log and training plans.