I was able to store all the parts for the Core and Expansion sets in the Core set's box by using resealable plastic bags. Solution might not be for everyone though.
Yup. I believe the metric used was that teachers and kids could build and program a robot in a 45-minute period. Do note that kids (and teachers) starting out with SPIKE Prime would not build as rapidly as an experienced LEGO builder would.
There is now, check out this video. Link here: https://hubmodule.readthedocs.io/en/latest/hub2hub/
Just thought I'd mention that the USB cable used to transfer programs from a computer to the SPIKE Prime hub also charges the hub. In my use case where I plug the hub in to program it, then unplug to run the robot, theoretically I'll never run out of battery.