They treat the text inside a comment as if it were actual code. You can't store file names in registers, and there are no frame configurations at all. The undo command in Emacs 18 is not careful about where to leave point when you undo a deletion. It ends up at one end or the other of the text just undeleted. You must be on the lookout for this, and move point appropriately.
Kill commands do nothing useful in read-only buffers.
They just beep. M-z c in Emacs 18 kills up to but not including the first occurrence of c . If c does not occur in the buffer after point, M-z kills the whole rest of the buffer. The function erase-buffer is not a command in Emacs 18. You can call it from a Lisp program, but not interactively.