starting with gnus

[harven]

I have finaly finished my gnus configuration file.
Everything is working fine, I still have some questions.
 
1) I tried to save outgoing messages in my unix mail box
   using an nnfolder. Here is what I put in my config file:
   
      (setq gnus-message-archive-method 
       '(nnfolder "my-saved-mail"
           (nnfolder-directory "~/mail")
           (nnfolder-active-file "~/mail/.active")
           (nnfolder-nov-is-evil t)
           (nnfolder-get-new-mail nil)))
      (setq gnus-message-archive-group "sent-mail")

   It works, but there is an useless empty directory called archive
   in my mail directory that reappears each time I send a mail.
   How can I get rid of it ?

2) Is there a mean to have the summary buffer self-update when
   new mail is received ?

3) The default color theme is a bit rough on my eyes. Do seasoned
   gnus users have some alternative set of faces to share ?

Thanks for your answers.