1) nylon straps w/fastex buckles
2) no, but you can put a trash compactor bag inside as a liner, that works fine
3) I usually just lock the bike to something, and don't worry about it. If it's a big city, you probably want somewhere secure - sometimes the visitor info center or chamber of commerce will let you put the bike in their office. Once I went to the movies and the theater let me put my bike inside in a back room. I almost never leave my camp pitched, as I move almost every day, so that's not a solution for me.
4) No, don't bother. I almost never need more than my 3 bike bottles, and if i do, i buy a bottle of water at the convenience store, use that bottle until i don't need an extra container any more, and then toss/recycle it. That way you aren't hauling around some big expensive container that you barely ever need.