for the font, it sounds the right format is otf.
and to get the font in a iPad :
<package xmlns="http://www.idpf.org/2007/opf" unique-identifier="bookid" version="3.0" prefix="rendition:
http://www.idpf.org/vocab/rendition/# ibooks: http://vocabulary.itunes.apple.com/rdf/ibooks/vocabulary-extensions-1.0/">
with
<meta property="ibooks:specified-fonts">true</meta>