Some questions of a newbie

[Cecil Westerhof <dummy@dummy.nl>]

I started using Emacs a week ago. It was always discouraged, but I need to
work with docbook, so I started using it. I wish I had done it sooner.
But there are a few quirks.
I am using 21.3.1.

I like to have the possibility to use the clipboard, so I added the
following to my .emacs:
 (define-key global-map "\C-W" 'clipboard-kill-ring-save)
 (define-key global-map "\C-Y" 'clipboard-yank)

First it seemed to work normal. I use C-w to delete something to the
kill-ring and C-W to copy something to the clipboard. I used C-y to get
something from the kill-ring and C-Y to get something from the clipboard.
But for one reason or another c-w and c-y did not work anymore, so I
disabled it. What could be the reason?

For comment I see that there is sometimes used one, sometimes two and
sometime three ';'. Does this has a reason, or not?

Is there a good way to find which keybindings are used, so a free one can be
coupled to a macro?

In my .emacs I have:
  (setq ediff-use-toolbar-p nil)

But the toolbar is still displayed. What am I doing wrong?

I added org-mode and nxml-mode.
The first uses:
  (add-to-list 'auto-mode-alist '("\\.org$" . org-mode))
the second uses:
  (setq auto-mode-alist
    (cons '("\\.\\(xml\\|xsl\\|rng\\|xhtml\\)\\'" . nxml-mode)
      auto-mode-alist))

Is there a reason for this, or is it just what the creator liked? If the
second is the reason, then I prefer the first way and will change the way
of nxml.