hey AH family its been a while since i've posted on here - last time it was discussing my subwoofer purchase! i'm now the happy owner (for now lol) of TWO HSU VTF3-MK3's

that i picked up for around 900 shipped.
BUT that's not the topic here - I'm looking to upgrade my entire 5 speaker surround sound system! I will at least break even w/ what I paid for the entire setup which is AMAZING! So I'll have all the cash plus around 500 to throw at my new setup.
Budget ~ $1000 for 2 mains, center, 2 surrounds
I currently have
Polk Monitor 70 II
Polk Monitor40 II (now sold)
Polk Monitor CS2 II (now sold)
powered by Yamaha Aventage RXA-3000
I have three questions
1. What brands/product lines should I be considering to replace the Polk Monitor setup I have? I would like to buy USED if I can (i've found some KILLER deals on eBay like a pair of B&W 683's and Polk RTIA7's for around 500 shipped)
*The goal is to step up big time in quality w/o stepping up big time w/ the wallet and from sold listings I know its completely possible!
3. I had monitor40 bookshelf speakers as my surrounds but both the 600 series and rti series, (and others i may consider i'm sure will) have true dipole surround speakers - should I forget the bookshelf options in those series for their dipole surround speaker options? (I think I know the answer to this but I wanted some input)
2. Would my AVR or the addition of an external amp be appropriate/beneficial to power my speakers? (side note - does anyone know if the yamaha automatically drives the speakers with as much power available or can you step up the power to the max?) I've heard monitors are "power hungry" and if they sound good its when they are played LOUD! Not sure if that's due to my AVR being unable to power the monitors adequately or what.
**The monitors are nice but i got spoiled by my dad owning legacy whispers, martin logan electrostatics, and having listened to wilson watt puppies and many other HIGH end setups so i'm not easily impressed anymore unfortunately hahaha

I'm looking for a speaker that can give impressive detail and adequate SPL's when played even at moderate volume.
So to start i've come up with two options that are higher end than my monitors that are still w/ in my budget - polk rti7 or 9 and b&w 683
educate me!