All the points you've raised have been covered forensically. from the day Corbyn reluctantly accepted standing for the Labour leadership to where we are now, further analysis covering something not already covered would be hard to find.
The reasons for people voting leave have also been forensically covered, sorry but your post comes across as RAWK dismissing any support for Corbyn or Brexit without going into great detail, these 2 arguments have been the most forensically debated arguments ive seen.
I've read the threads and to be honest all I've seen is one way traffic, I was involved in some around the time of the referendum and any post hinting at a Leave opinion was angrily dismissed, I appreciate emotions were running high. If you can point me to the specific debate on immigration, then I'll quietly go away and read it.
I'm not trying to cause trouble, I think that one of the reasons why the Leave vote happened is because open and honest debates never happened. I remember watching a TV debate with Anne Sodbury basically calling somebody a racist for even raising the immigration issue, so guess what, everybody clammed up and the open debate never happened, doubts and questions were never quashed or reassurances given. The doubters simply walked away and voted leave.
I speak to a lot of Leavers, the North West is predominately Leave and I'm quite frank with them in trying to understand their thought process - not dismiss them. Try it, talk to them and I'll tell you want I really don't see any sign of a great shift towards Remain, many now want No deal, they feel angry about not being listened to. Again, the voting numbers were big, most areas around here were 60-70% Leave - that requires quite a big turnaround.