How can I avoid dry scaly skin on my feet: could it be athletes' foot?

Dry scaly feet. It could be athlete's foot or atopic dermatitis or contact dermatitis, etc. You can try to prevent athlete's foot by wearing sandals, changing shoes/socks often and after exercise, using foot powder, washing and drying feet often, and avoiding wet public floors and wearing other people's shoes. A dermatologist will do a KOH prep of a scraping of your skin to confirm the diagnosis. See one.
Depends on cause. If it is simply dry skin - moisturize. It can be a fungus in which case an antifungal would help. It could also be eczema, you can try an over the counter steroid preparation. If after trying the above it remains consult a podiatrist or dermatologist.
Urea Creams. To keep your feet moisturezed use a good urea type cream like lac hydrin or am lactin. It is best to apply them after bath or shower when the skin is hydrated. Athletes foot would cause severe dry cracked skin and redness on the bottom and sides of the foot. If this is the case you should see a podiatrist for treatment.