How do I know where to go next when I get an upgrade? I end up going around and around in circles, trying to find out where the next upgrade is. Maybe if the maps were a little clearer on if there were any upgrade coins in the area, or there was some way to tell where you should go next (like, the general direction, or something)

There is also the ancient maze scroll... It is like tiny map containing all the routes the algorithms took to place the upgrades in the world. You have to search for it at the outer rings of the world.

I can't remember which update it was, but now all the coins you haven't collected are displayed on the minimap. When you scroll through the map, you will see there is one coin spinning. That is the one you will likely have to find next to proceed in a timely manner.