I know virtually nothing about rivers so that is the biggest reason for the strangeness of the rivers. Part of my explanation of the rivers though is many of them go into the mountains into underground rivers which leads to the oceans. The other part of the explanation is...It is a fantasy world so if things aren't realistically the, who cares.

Actually the cities are just on top of the tree symbols. I may go and remove the trees, though I doubt it.

The circle land in the middle is Ring di Waph which in Draconic means Ring of Life. Dragons believe that all life started there. It is also the only continent that is not a fractal. It is virtually a perfect and smooth circle because the gods made it that way.