1. There was no analysis by a media firm hired by the Big 12 that showed UConn was a net benefit to the conference, b/c we ARE the company that does analysis for the Big 12, ACC, SEC, and Big Ten. We don't do work for the Pac 12 or Big East. EVERY team analyzed failed to meet the minimum "value added" to extend a membership offer.
2. UConn isn't a fit for the Big 12, but cultural fit has been overlooked by every conference expanding. Utah & Colorado don't fit the Pac 12. Rutgers & Maryland don't fit the Big Ten. Missouri doesn't fit the SEC. Boston College doesn't fit the ACC.
3. You're right and wrong. The ACC absolutely felt UConn was a viable expansion candidate. However, it's not as straight forward as you believe it to be. The ACC wanted to expand b/c they wanted their own network. In order to get their own network, ESPN required (a) more inventory and (b) a signed Grant of Rights. So the ACC expanded with the belief that they'd make money by signing an all encompassing contract with ESPN (i.e. ESPN controlling all rights for all sports) with a conference network. As such, UConn, Pitt, Syracuse, Louisville, and West Virginia (the teams they vetted) weren't held to the same financial standard they would have had the goal not been to get the inventory required to land a conference network agreement with ESPN. Also, this was during the time the Big 12 was flirting with Clemson & Florida State through back channels. Though the Big 12 was unstable, they made significantly more than the ACC. That money + the flexibility of owning your own tier 3 rights was an attractive pitch. FSU's new President really wasn't interested, but key people at Clemson were. And, Miami reached out themselves to gauge the Big 12's interest in them (there was no interest from the Big 12). So the ACC wanted the Grant of Rights to lock everyone in. Point is, there were a lot of factors pushing the ACC to expand, secure Notre Dame, sign a Grant of Rights, protect against departures, and land a conference network.
As I mentioned above, though the ACC got what they wanted in terms of expansion, Notre Dame, etc, the conference network didn't work out. First, ESPN stonewalled them for 4 years before finally signing a developmental deal with a flexible launch date. ESPN then pushed that launch date out as far as was possible (3 years). So the money they thought they were going to get from expansion didn't materialize. And even now, with the ACC Network launching in 2 months, the ACC is still woefully behind the Big 12 in annual payout (and crazy far behind the SEC and Big Ten).
Now, the ACC has the benefit of hindsight. If expanding today, UConn wouldn't make the cut. Neither would Pitt, Boston College, et al. So it's not that the ACC didn't once think UConn was a financially viable addition, it's that today, they now have a different perspective and the benefit of hindsight. As I've said before, when expanding, any incoming member needs to add MORE $$$ to the conference's TV contract than they will receive once they are a full member. Otherwise, each current member will have to take a pay cut once the incoming member(s) becomes a full member. For the ACC to extend an invitation to UConn or any other program TODAY, that program would need to increase their ESPN contract by at least $30M/yr. The American Athletic's new contract will pay out approximately $84M/yr total. For UConn to be worth $30M+ per year, they would need to account for more than 35% of the AAC's new contract, with the other 11 teams accounting for less than 6% of the contract each. No doubt UConn is the most valuable or one of the most valuable members of the AAC. But they aren't accounting for 35% of the AAC's contract with the football program ranking in the bottom half of the conference in TV ratings. TV ratings are what drive the contract's values.
Anyway, I hope that adequately addresses your questions/concerns. Best wishes to you guys moving forward. Give it 3-4 years and you'll wonder why your leaders didn't make this move sooner rather than later. I can tell you, you absolutely will end up with more $$$ when the dust settles. That AAC contract is based on 2019 dollars, while the NBE contract is based on 2012 dollars. HUGE change in the market over the last 7 years.