Oops forgot about the raised 7th. I knew I would forget something. To tell you the truth I don't know the exact science behind why the 7th is left natural, maybe because of the b6-7 harmonic minor similarities or my guess because F and Dbmaj are both major tones relative to there key note, C major. E is a major seventh to F, and also natural in C major (E not Eb). Or it could be because of the need for a leading tone to F, I dunno exactly why. Point is it sounds more compatiable and better as E than as Eb. Go figure!

My personal experiences with it, the F lydian scale doesn't work well probably because of the unnatural occurs when the Neapolitan chord is played (bII). I can think of several reasons why but just don't know exactly the reason.

As for being to text book. You asked me what I knew so I gave all the facts that I was aware of. Didn't mean for it to sound textbook. Hard to write it conversely at that point. Just me I guess. :)