Current questions and answers regarding the map editor.

The sparkles are actually effects. During the game, set the camera vertically, hold down Ctrl, and you will see the coordinates near the cursor. Remember them (or write them down), open the editor, and delete what is there (if you don't see anything, still select the cell with these coordinates and press Delete, that's what I would do).
Black water? In the second screenshot, everything looks normal. Just in case: if you are creating water using water (in Terraforming), the color of the water depends on the color of the surface underneath it. If you use Terra skin->rivers->water, it doesn't depend, so you can cover the first water (like the sea) with the second for aesthetic purposes.