I picked up a low use 65-VT30 for $600.00 last year and have set up a second HT sound around it - could not be happier with my buy.
Reviews point to what Owen said re Panasonic Plasma internal tuners softening the image and the use of a set top box as the solution. Not a concern for me as the Pana 65 is 99% streamed from the home server..
My understanding is that Windex is a big no no as it contains ammonia and will strip screen coatings. Use an ammonia free spray for any screen.
I have not bought the MiniDSP units yet. I was actually after them for active crossovers between mids and highs so I can upgrade the current 2CH amp modules I currently use. I have had a play with them a few years back.
You do not need an AVR to do the bass EQ. If you have a DSP between the AVR and subs, you can use MSO (Home page) to calculate the PEQs. The documentation is extensive, plus you are more than welcome to post or pm me with your questions.