I am not a lawyer, but I had a couple of comments on your comments:
Actually, to my knowledge inserting the d20 STL license is not part of the requirement; only the trademark, the "This product requires" boilerplate in no larger than 12 point font, staying away from the prohibited subjects, and abiding by the quality standards. Only the OGL makes a requirement of the license, and the product must be OGL if it's part of the d20 STL anyway.
Not to dissuade you, but it does seem reasonably clear to me: basically, anything that is not a mechanic is protected property. With that statement, they released the MECHANICS to their feats, spells, etc. But not the names to such. According to that text, if it's a mechanic, it's open; if it's not a mechanic, it's not.