How long will they be?
That diameter is probably pretty stiff so can handle a pretty large span without sagging.
That's a good question. I'm still figuring out my layout.
Either 8 or 12 feet, depending on how we partition the space. (There's going to be a 4x8 grow-out/integration facility in one corner).

Well, except the new house. That will be concrete. But for the animals, sheet metal is just fine.