If you want to make the symbols into Custom Shapes, then Illustrator will probably make things easier, although I don't know the workflow for importing the shapes into PS. And the hexagon and star will be easier there than in Photoshop. If you just want brushes, though, the rest of the symbols can be fairly easily made with rectangular and circular selections which you stroke and/or fill. Once you have the symbol constructed, crop the image down, flatten it, and go to edit > define brush preset. I'd suggest you make your brush quite a bit larger than you'd ever actually use it so you don't lose any quality if you decide to make really big city icons for some reason, or you work at a much higher resolution some day down the road.