You can clone with
HTTPS or Subversion.
It's impossible to enter directories or open files whose name starts with a #
are you trying to access this from the browser? the browser doesn't even send the hash portion of the URL, so you'll have it escape it yourself.
I believe he means that if there is a directory on the server named #blah the URL to open that directory when looking at the parent directory includes a literal #, and so the client doesn't send the # and everything after it.
The browser will just request /dir/ because of this.