Many of those cheap black plastic pedals are so bad they don't even have ball bearings inside. Just the plastic body turning directly on the steel axle shaft. Pry the end cap out and you often see a washer welded on to the end of the axle to keep the pedal body on. The harder you pedal the more friction and the more of your energy you waste. If you goal is exercise, no problem. If you want to go faster, get some decent pedals. Avoid the metal plates screwed to plastic bodies type. All cast magnesium or cnc'd aluminum alloy is a great step up.
Shoes: I find I have to try them on. No mail order for me. My feet are shaped oddly and many shoes just don't fit at all.