James Clark, editor of the working draft on XSLT - The XSLT WD that has just been released allows a stylesheet to output a DOCTYPE declaration with a specified system and public identifier by using the doctype-system and doctype-public attributes on the new xsl:output element. See http://www.w3.org/TR/xslt#output
A good paper or article on XSLT http://www.xml.com/1999/04/holman/gkh-19990418.htm
Subscribing to the following is of immense value: http://www.mulberrytech.com/xsl/xsl-list
One of the postings to that list includes a number of XSLT resources: http://www.mulberrytech.com/xsl/xsl-list/archive/msg06313.html
One simple additional step to take is to dynamically generate your XSL, just like you dynamically generate your XML. It is XML, after all. Then you end up with an XML doc that contains the bulk of the data for the page, and then an XSL document that contains the formatted 'container' for that data, with menus and so on, but with the advantage that much of the HTML in the rules has been added dynamically. We have used this technique on http://www.worldlink.co.uk/ if you want to have a look.