I think most ppl have a adress in their home-country. They also have banking and other stuff there. But if they are staying som-were, they do have a adress while applying for the visa. They are not living on the street 🙂. But you really got a good point. TIT my friend 🙂
answer question no1, this visa is not for permanent stay, so I think they want some proof of homebase. If you are written in a place, perhaps family or friends, you could use that. I mean most ppl do have adress?