Very well thought out. A lot to digest so the only response I can offer is a personal experience. I joined the Labour Party in order to vote for Jeremy. I joined properly, not just paid £3. I had to resign my membership of the Green Party. I was very enthused, so was my husband. We had recently moved from a Labour area to a Tory heartland so decided to attend meetings and get involved.
Not knowing what even 10% of the acronyms used in meetings was my first problem. Not knowing how a political party functions, its rules etc. further isolated me from the proceedings. It wasn't at all what I expected. No talk or debate about policy or ideals. Just a core of around 15 people, all of whom knew all the acronyms and were fully engaged.
I attended six meetings before I gave up. My husband managed just two.
The most puzzling thing of all was that in those first meetings after Jeremy took the leadership there was quite a lot of comment about how many new members had joined the party locally and how important it was to get them active and engaged. As far as I could tell there was us and three others who were new “Corbynistas”. It was briefly acknowledged. But nothing was actually done to help integrate us, or give us anything to actually do.
There was a lot I wanted to volunteer to help with: street stalls for example. But I feared that I would not be able to answer questions from the public. I needed training, but none was available. Until there is an introduction to party membership for new members I imagine thousands of us new to it will drop out and not attend meetings.