Metal is one of those materials that requires specialized tools, mostly electrical. Some are more of a luxury than a necessity, but others are fundamental.
Stairs can be made out of metal, wood, concrete, bricks, dirt. Depends on what you want and where you want it.
Windows and doors are essential for both light and breeze, not to mention access. You want to position them for maximum gain.
There is almost nothing faster than a metal roof, so if speed is your priority, metal is a great option. However, it is expensive, not particularly durable, heats up in the sun and is loud in the rain.