Keep your shoes clean and dry by washing them, rinsing well, then air drying. I've documented my own home-built set up for you here. Yep, that is all. I run 3-4 times a week. If I feel the need for speed, I'll substitute a longer scheduled race for a fast 5K. Even right before or right after a marathon.
Swimming is an excellent way to recover from ultras or marathons, and to cross train.
There are many ways to get access to pools. I like to alternate swim, run, swim run as it seems to lengthen the muscles that running pounds down. Walking is fun and a wonderful way to stay active, keep the metabolism cranking, and stay stretched out. I walk once or twice a week, sometimes before yoga if I'm achey or stiff. My weeks follow pretty much the same pattern, but I'm very flexible and not at all hesitant to change a workout, or the whole week, on a whim.