EU referendum, brexit and the aftermath

Is this wrong?

It's not obvious to me. That's their explicit position when a 'Tory Brexit' is on offer; i.e. when they're not in govt.
From what I've seen they're less explicit when they're in power - I suspect that they'd take an election win as a mandate to go ahead with their interpretation of Brexit and not necessarily with a referendum.

My understanding - Labour will try get a better deal, but whether any deal be good, bad, indifferent or exactly the same, it will go on a referendum alongside remain. Is this wrong? If not, why is it a bad thing?

My understanding, from listening to the radio so may be somewhat out of date, is that Corbyn has laid out his policy for no deal and the current "bad Tory deal", but he's said nothing about what Labour is committed to do if they win a GE.

Which means that unless and until he does bring clarity to that the current (stated) best chance of a referendum is to hope that a Tory minority government struggles on.