We have now completed step by step instructions on how to build the Funfort and we entered it into the Instructables "Holiday Gifts" competition.
Wood is one of the oldest fuels for heat and cooking. If you have it locally available, it can be an invaluable source of energy for your homestead, even as a source of electricity.
Wood is a softer material than metal and can handle a lot more hand tools, which are generally cheaper.
Stairs can be made out of metal, wood, concrete, bricks, dirt. Depends on what you want and where you want it.
Wood is cheaper and easier to use than metal, but metal is both stronger and more durable. The quality of the wood is one of the most important factors, so see what you have locally available.