6:02 AM, Thursday December 24th 2020
With regards to the gaps, boxes will look smaller and further away from the viewer if the gaps between them are quite small. Notice for instance in this photo, the pillars of the bridge appear to get closer together as they go back in space. Logically we know that they remain the same distance apart from each other but as things get further away, space compresses as it approaches the vanishing point. It's not a big deal if you don't understand it yet since the organic perspective exercise is intended as an introduction to these kinds of concepts and will be something you start to grasp more and more throughout the course.
As for the divergence, this is what happens when the parallel lines of your boxes do not converge evenly towards their shared vanishing point, instead one or two of those lines go towards their own vanishing point. This is something directly covered in the 250 box challenge however.