Thanks for the compliments.
I wouldn’t worry to much about the bearing thing until you get all the pieces. Then go step by step following the instructions and you should be okay. The center is a tricky piece and needs to get assembled in the right order.
The z bearings should and will flex. They have to move. Each part has a bearing group that moves to compensate for alignment and conduit surface finish.
ABS is tricky and can shrink in a bad way…