She therefore adopted the anti-free-movement position, which condemns the UK to being outside the free trade area, and completely blows up the Ireland situation.
What "should" have happened is one of Johnson, Davis, or Gove running it. Or, after the Tory Party elected a Remain leader, she should have stayed Remain and run a GE on that basis. If people wanted Leave they would have had to vote in UKIP.
IMO, whoever was in charge, it should have been done like this: 1. Nationwide consultations about type of Brexit; 2. Determine best fit; 3. Work out negotiation objectives and fallback plans; 4. Then invoke A50.
They have suggested they would be open to alternatives when Corbyn approached them earlier this year. If a general election or new referendum had taken place, I think the EU would have granted an extension to hear what new alternative would emerge.
They are saying TM's deal is the only deal now, but that's because it was negotiated exhaustively in private already, and TM told them, essentially, she would take it to the MPs to get it rubber-stamped.
The MPs said no, it's their job, not hers, to hash out the big important compromises for the country, she should have consulted them before getting to that point and they don't like the deal she made, and they rejected it with the strongest defeat in parliamentary history.
The problem is leaving consensus building so late, so the EU spent all their negotiating efforts on TM's version of things, and they don't want to negotiate twice (unless a really good reason shows up that lines up with their principles).
Ah, that's news to me. Do you have any more info, like an article explaining the potential alternative models?
It's really the prime minister's job to build this based on working cross-party, but an obvious example might be a relatively close Norway-style relationship, which would be much more likely to receive opposition support.
I don't think anything better than the current deal is even possible
This is again just absolutely false.