First, let me say I assumed this was about the Windows XP fonts.
The simplest way to find the owner of a particular font on your system is to check the FONTS folder and double-click on the name of the font.
Certain typefaces are obviously owned by Monotype, like Monotype Corsiva, and even taken-for-granted ones like Times New Roman, Garamond, Arial, and Courier New, Symbol. I'm not sure about what others are included...
Including an unaltered font means including the original un-named TTF file...
Embedding as a subset probably refers to PDF/DOC documents that break the font up and uses only the characters needed to read it. I notice it doesn't say anything about the right to distribute these files publicly.
Here is Monotypes official page that clearly states you need a license to embed their fonts in eBooks:
http://www.fonts.com/FontPackages/_e...tSolutions.htm