No, we do not have multiple template support per page. RSS is not currently supported, but slated for next release.
We did full XHTML compliance testing back with the 4.0 release; but we may need to recheck all our pages since we've had a few releases since then. The majority of HTML code is in the templates. We'll plan a full suite of compliance testing for the next update.
Please do not PM me for support or sales questions. Thank you for your understanding.