Thanks BalbC
That's a very thorough run down.
I've visited Tokyo whilst using a wheelchair before so had experience using trains and buses that proved useful when taking the stroller (which we ended up using more than anticipated as my father-in-law's sciatica was bad and the stroller provided relief on our excursions).
Your comments about splitting up at elevators are spot on. On the odd occasion there would be a short nervous moment because the elevator would go somewhere completely different to the stairs/escalators causing a delay to our reunion on the other floor, but splitting up when there's a push for space is definitely the courteous thing to do. Also, wheelchair users get priority as far as I'm concerned (they have to deal with delays at the gates and at the elevators every day).
The Quincy Zapp is definitely too wide for some gates (and even some escalators, there's one at the entrance to Azabu Juban that comes to mind) and certainly needs to be folded to board a bus. Then again, it's too wide for some buses in London.
And the documentary thingy I saw was definitely "a view" rather than "fact", but interesting for me to see at least one way that a habit that I had found myself to be a minority in practicing was supported and encouraged in another culture. Stroller type A is a device that I've never been able to get my head around, makes no sense to me whatsoever under anything but some extreme and freak circumstances.

Multiple infant carriers are something I see quite a lot of when I'm in the Minato Ku area. So whilst the two tier twin and sibling carriers aren't something I've spotted very often either (much more common to see two kids mounted on a bike) 4, 6 or even 8 kids on a sidewalk tram is something I've seen regularly. These are usually kids at kindergarten being escorted around. Occasionally you see a large (generally foreign) family being towed behind a parent in a big wheeled box with seats.