emacs and UTF-8

[knubee]

I'm trying to find some summary explanation of the different ways Emacs
handles UTF-8. There seem to be many different possible settings
(set-language-environment and set-default-encoding-system and ...) --
and there seem to be distinctions between reading, displaying, writing,
etc. I have not been able to find anything that explains these
distinctions. So far, I haven't found a way to set one variable
somewhere so that makes everything within emacs read, write, and
display UTF-8. Is there such a variable?

At the moment I am able to write and display Swedish characters within
Emacs. However:

- if I reply to an email, the cited version will be full of junk
characters instead of the Swedish characters (which display fine in the
original email I recieved). My mail application is VM, if that makes
any difference.

- if I run a Scheme program on a data file that includes Swedish
characters, the returned values will include junk characters for the
Swedish ones (and again, in this case, I am able to open the file and
see the Swedish characters perfectly).

Aside from solving these *particular* problems I would like to find
some good *model* for how Emacs handles UTF-8.

I'm running Emacs 21.3 under Debian, and below are some settings from
.emacs file.

(set-language-environment 'UTF-8)
(set-default-coding-systems             'utf-8)
(setq file-name-coding-system           'utf-8)
(setq default-buffer-file-coding-system 'utf-8)
(setq coding-system-for-write           'utf-8)
(set-keyboard-coding-system             'utf-8)
(set-terminal-coding-system             'utf-8)
(set-clipboard-coding-system            'utf-8)
(set-selection-coding-system            'utf-8)

thanks for any help.