MindWare Q-BA-MAZE 2.0: BIG BOX SET

The photo shows that this is the Q Ba Maze 2.0. Is that correct? I'm asking because the title didn't actually reflect this. Many thanks!

what size diameter are the steel balls?

Is this maze easy to take apart and put back together? We don't have a lot of space to set it up and leave it set up.

What add-on would you suggest for the q-ba maze big box? my grandson loves marble runs and does a great job of building.