By default, when you visit a .html file in Emacs (22 or 23), it will put you in html-mode. That is probably not what you want. You probably want nxml-mode, which is seriously fancy. nxml-mode seems to only come with Emacs 23, although you can download it for earlier versions of emacs from the nXML web site. There is also a Debian and Ubuntu package named nxml-mode. You can enter nxml-mode with:
M-x nxml-mode
You can view nxml mode documentation with:
C-h i g (nxml-mode) RET
All that being said, you will probably have to use something like Tidy to re-format your xhtml example. nxml-mode will get you from
to
but I don't see a more general facility to do line breaks on certain xml tags as you want. Note that C-j will insert a new line with proper indentation, so you may be able to do a quick macro or hack up a defun that will do your tables.