Can I recover fonts, Book Antiqua for example, from an earlier OSX that doesn't seem to be supported by Mountain Lion, since I did a clean re-install
You'd have to retrieve it from a backup, or reinstall apps which will put it back on the drive. OS X did not supply any version of Book Antiqua. Oddly, OS 9 did.
But otherwise, Book Antiqua will be installed by MS Office 2008 and 2011.
Retrieving data ...