My guess is that MM likes to let it all hang out, and Jorge likes to be more on the bike. A wider base tank would make it easier.
I'm guessing the design and location of the "hard parts" takes precedence over the location of all the electronic bits that will all be figured out later. For now they just marmalade all that shit in a tupperware box up under the tail section. I woulda though the new Honda seat for Jorge and Marc would have looked more like a 2up banana seat of an old F4.
it seems that this arm/lever is attached to the front of the swingarm through a linkage. any wild guesses?
From your previous picture, it looks like they're reacting out the braking forces through that reaction arm rather than through the swing arm. I'd imagine that it needs to have a pivot that's in some way coupled to the swing arm in order for the two to have the same arc through the suspension travel.