We had the factory visit and HB130 test ride on Tuesday, so I reckon I can answer a few of those questions.
The BB is a tweaked version of the Hope 30mm one – uses the same replaceable bearings, just a slightly different sleeve. Being Hope, you’ll always be able to get parts.
Rear axle/spacing – I can’t see anyone looking to run anything other than Hope hubs on a Hope frame, so having something specific makes sense here – Hope were keen to do what they saw as best, the frame axle doing both jobs seems a decent solution.
The brake change is because they’re doing a framset option for the HB130 – frame/headset/hubs/BB. Again, I think a Hope fan will run Hope brakes – but there’s at least the option to bolt something else on.