I can help with a few of your questions.

You are on the right track by looking at the NTEP results for trial sites located near you.

I have gotten seed from Hogan Farms in TN. They have a lot of the top varieties available and are reasonably priced. You can goggle them and give them a call. There are other good seed suppliers also.

The reason it is suggested that you use a mix of grass varieties, say three varieties, is that it is sort of like insurance if one variety is more susceptible to a disease then it won�t wipe out you whole stand of grass (genetic diversity). You will want to select grass varieties that are similar in color and blade type (e.g. fine, etc.).

I don�t grow KBG so I can�t help with specifics about that. I do know that it will self repair bare spots via rhizomes very well where as the jury may still be out on the newer TTTF varieties spreading by rhizomes.

Hopefully some regulars on this forum will reply with more specifics than I can give you. I do know that time is getting short for doing a renovation in your area this year.

"I have 20,000 sqft to overseed, so what's the best (cheapest) place to buy?"

Most seed prices are fairly consitent with most internet seed sellers, except Seedsuperstore which charges a lot more than most. The Hogan Company has good prices and the most TTTF cultivars available. Williams Seed and Pawnee Buttes have good prices, and good KBG cultivars available. Whenever you buy seeds ask for sod quality.

"I am thinking of mixing an 80/20 Falcon V to Midnight ratio as I mostly want fescue's drought tolerance but also want some bluegrass for spot repairs. Is this a good custom mix?"

Probably not. Midnight is one of the darkest KBG cultivars, and it doesn't grow all that fast. You lawn probably won't be very consistent in terms of color and texture.

" Is mixing in any bluegrass necessary given that Falcon V has 7%+ rhizomes already? I see some people mixing in 3 types of fescues instead of just 1--should I be doing that?"

Rhizomatous Tall Fescue is more marketing and hype than anything else. All TTTF spreads to some extent, RTF doesn't spread faster than regular TTTF (at least a study in 2005 showed that. The newer cultivars might spread a bit faster). I have a small area of one RTF, Firecracker LS, and it spreads mainly by vigorous tillering, although I have seen a few daughter plants but it's nothing to write home about. If you want self repair, nothing beats KBG...yet. You can mix three separate types, but it's not as important as it is with KBG, but you get a little genetic variation that way.

"What's the deal with the tags--blue tag, gold tag? What kind of tag should I be looking for when buying my seeds?"

Just ask for sod quality.

"A colleague of mine from work says that I should overseed with RTF Fescue from Tood Valley Farms.
http://www.toddvalleyfarms.com/RTFTurfSaverSeed.htm
She has it over her whole lawn, raves about how low water and maintenance it is, and wants her soccer club to even use it to seed their playing fields. My dilemma is RTF Fescue is not rated by NTEP. How does it compare against the Falcon V's and such?"

Most TTTF's perform similarly as there is less genetic variation, although there are obvious some that look better than others. I would trust the NTEP, and if you want an RTF buy a highly rated one.