Tall Chords And Their Treatment.

1.  I'm trying to figure out the modern (academic) treatment of tall chords (chords with the 7th, 9th, 11th, and 13th added or any combination thereof) in TONAL music.  Is there a point in history where the great classical composers stopped caring so much about the chordal 7th?  My textbooks say that the chordal seventh should almost always resolve down by step (except when the major seventh occurs as the result of a suspension from the previous chord, in which case it can resolve upwards, or it is treated differently in some voice leading circumstances), but is there a point where composers stopped using chordal sevenths as a dissonant tone that had to be treated with such care and it became more or less equal with the other tones of the basic triad and could move any direction or even leap away (in classical music, not jazz)?  If so, for stylistic accuracy and my own edification, when in history did this happen (if you know)?  Did the dominant 7th ever achieve this status as well?  When writing chordal 7ths (of all types) in modern tonal music, should I still resolve chordal 7ths carefully with the main exceptions only occuring when I have some other specific reason or purpose in doing it differently if I want to be academically correct?

2.  Also, I've learned that all other chord extensions (the 9th, 11th, and 13th) should also be treated carefully if they are part of a functioning harmony and should almost always resolve downwards as well.  Is this true if one desires to be academically correct?  Or should I be allowed to go upwards and leap away in a modern tonal context?  Or should I just USUALLY resolve down as the most general rule and only do differently when I have a reason or purpose in doing so?  Does anyone know when tall chords started to become common to use so that I might have the knowledge to remain stylistically correct as to the musical era on this as well?

3.  In addition, I have questions about the treatment of tall chords contrapuntally.  When you have strings of chordal 7ths, it becomes more difficult to avoid parallel 5ths, but I know that you are still, nonetheless, expected to do so.  When you have chords that ALSO contain the 9th, 11th, or 13th, and then you have one tall chord after another, the task of maintaining a complete lack of parallel 5ths starts to seem somewhat daunting and excessive.  Academically, am I still expected to do this and I'm just being lazy?  Or is there a point where composers using tall chords in a TONAL context literally just said "ah, screw it" and stopped caring so much about parallel 5ths?  Again, (if you know) about when did this happen historically?

4.  As far as the treatment of tall chords in arranging goes, I have another question.  Obviously the standard 4-part writing becomes insufficient to articulate all the tones of a complete 9th chord (and above).  If you are going back and forth between tall chords and 7th chords or triads, can you literally "add a voice or two or three" for the taller chords and then simply have that voice/those voices collapse into just 4 voices again for the triads and seventh chords so that you don't have to deal with writing 5-part, 6-part, and 7-part harmony on triads?  Or is the temporary occurence and elimination of the extra voice/voices considered an academic immortal sin?  Speaking of which, my understanding is that you are still expected to avoid parallels in 5-part harmony and up, but that contrary 5ths and octaves (consecutive 5ths and octaves that come about as a result of contrary motion rather than parallel motion) become permissable.  Is this true?

Any answers to any part of this will be much appreciated, even if you cannot answer all of it.  Thank you guys so much for any help you can give or any knowledge that you can share.  Also, if you happen to know of any texts that extensively cover the most modern treatment of tonal harmony and/or counterpoint (rather than treating it as some sort of side-note or only devoting a chapter or two) that actually answers these and similar questions about the modern treatment of tonal music, then please let me know.  But please include the title and the author so that I can easily find it when I search for it for purchase.  Also, please keep in mind that my questions are regarding the classical treatment (rather than the jazz treatment) of these things.  (Also, please no generic responses of "there are no rules, do whatever you want" or "follow your ear".  I'm asking from the academic "correctness" standpoint, and I'm aware that I can do whatever I want in my own music.)

Look for impressionist music. It's still tonal and doesn't worry about these annoying harmony rules. Check out Ravel's works and you see tons and tons of unresolved 7th chords, 9th chords etc. Debussy (and Respighi) are also good to listen to^^

Here's a nice place to understand more features of impressionistic music:
http://academic.udayton.edu/PhillipMagnuson/soundpatterns/microcosms/impressionism.html

Hope this helped somehow