JBoss Tools should support Seam 2.3.Final but it's not released yet. You can try a nightly build from http://hudson.jboss.org/hudson/job/Seam-2.3.X-nightly/ so far.
Regarding your question about Seam 2.2 + JSF2 it's better to ask Seam comunity https://community.jboss.org/en/seam/seam2