1. I used a black steel toe boot (9" I think?) but I either should have scaled my boot armor larger or just used ankle high boots instead. I'm going to go with the latter, since pepping the HD boots was a pain. It'll really allow more freedom of motion too.
2. Tons and tons of fiberglass. My boots took a beating, but never fell apart. Using the 3 piece HD models, I used nylon webbing on one side to hinge the top of the heel to the bottom, and a buckle on the other side to secure it. As for attachment to the actual boot, I used lots of hot glue. Next time, I'm going to use nuts and bolts to attach the heel and screws to attach the toe for permanent attachment. Also, if I could find some kind of pvc plastic sheeting to go on the bottom for sturdiness, and foam for treads.
3. I'm going to use ribbed vinyl, but I was thinking also these could be used:
Corrugated drain pipe is cheap and you can find it everywhere.