"You said that the #5 and #9 where the flat third and seventh of the next chord ie. Cm , well this makes sense, so, functionaly they are there to create a dissonance which resolves into the C minor chord? Is this the function of these extensions?"


That's pretty much how I see it. Generally the extensions should fit the melody as well but primarily they are their to enhance the tension properties of the chord and to smoothly progress to the resolving chord.


"I always thought of the A section of RC's as fundamentally major diatonic in tonality (1625 ) and see the third chord as a DORIAN minor which would not give the particular chord you are talking of as the 'V chord of the II chord' this would be another 'simple' minor in the Aeolian position (natural minor) both dorian and aeolian have perfect fifths, flat thirds and sevenths they only vary in their sixth tones. So you are talking some other kind of minor? "


Secondary dominants by their very nature (as in the V of II instance ) shouldn't be seen as having to conform strictly to diatonic note choices. Therefore it isn't a question of having to justify certain extensions with reference to modal degrees. The V of (dorian) isn't intended to be seen as an aeolian chord any more than say a passing diminished 7th chord on the bII degree is strictly a diatonic chord. In each case they are used because of their resolving tendencies.

You could claim that, taken as whole, any one bar of II V constitutes a temporary key centre, and that's an option you have as a soloist to treat it that way, but over the course of a 4 or 8 bar phrase its still fundamentally about a progression supporting a melody in a given key.

Alan