and how can I print the blueprint of the statusline?
set statusline? prints blank (statusline=) which doesn't seem correct to me as my statusline shows filename, row and column numbers as well as "All" or "Bot" at the end.
set statusline?:help statusline shows the documentation while set statusline? just shows its current settings (not what the stuff means). These are actually documented in the ruler option (so :help ruler), which is kind of the default statusline if you don't have one set. I think :-S
Botmeans you're at the bottom of the file (last line). All... depends on its position and your statusline configuration.