1) Are the fonts properly listed in the OPF manifest? I assume they are, but it's an obvious thing to check.
2) Does the rest of your styling appear in ADE? If ADE finds an error then it throws out everything, so if any styling appears it indicates that ADE has successfully parsed the css.
3) These are display fonts that you're probably using for headings (I hope
), are the classes (calibre10, calibre28 etc) properly applied in the xhtml?