How do i Redirects users back to my forum?

[Eikinskjaldi]

What dismounted said. Basically, dont mess with 404.

As for the other question, put this in your .htaccess

RewriteEngine on
RewriteCond %{HTTP_HOST}   !^www\.mysite\.com [NC]
RewriteCond %{HTTP_HOST}   !^$
RewriteRule ^/(.*)         http://www.mysite.com/$1 [L,R]