Are you talking about the standard chat windows that open when you connect to a new server (status window in that case) or join a new room (channel window) or are you talking about custom windows that (usually) start with the @ symbol?
From you request, it looks like you mean custom windows, so the items you should look up in the help file are 1) /aline
2) I don't know since I can't find anything regarding an input field for custom windows
3) $sline
Both /aline and $sline (as well as a whole mess of other commands and identifiers for working with custom windows) are all in the help file under /help Custom Windows
