First some answers than a rant
1: 404 handling is either done on the reverse proxy, the appserver, in the webapp (last 2 both plain jee), or like in your 'example' seam (when there is an ENFE, a 404 is send back)
2: search the forum, has been discussed multiple times before. One of the possible causes is even in the wiki: http://wiki.jboss.org/wiki/Wiki.jsp?page=SeamProblemsFAQ
3: Yes, according to google (which really is your friend)... I (major capital I) found http://www.michaelyuan.com/blog/2007/07/24/seam-20-and-tomcat/ as the SECOND result from google.
wow.... two 'seam questions' in one weekend in the seam forum... coool... this one and
oh wait, there is also
but this one contains 3 questions... of which one is a duplicate of the first post... how many 'seam questions' does that make? ;-)
I personally would appreciate it very much if you post questions with at least a relevant subject and one per subject so I and others can easily decided whether to look into this specific post or not.
Thanks in advance and have a nice *weekend*....