Veronica is right....... switching pedals is really easy with a pedal wrench. If you buy one at your LBS, ask them to demonstrate how to use it. Just remember, you always tighten the pedals down in the same direction as you pedal. You loosen them by turning the opposite direction, which means they are threaded differently on opposing sides.

Isn't there some type of adapter that would allow for use of speedplay cleats on your sandals? Check on the speedplay website (you can always google it to find it) and see what they say.......