The grid button only controls the drawing aid grid to help you layout the drawing. What you have there is an in-drawing grid, a grid that is intended to be part of the drawing, which usually live on the GRID sheet and can be hidden bust by hiding the sheet (or the HEX/SQUARE GRID layer).

I accidentally scale often myself. The solution I find works best with both regular move and quick move is to just keep my hand completely off the mouse until I have released all keys.

The commands for the regular move command is MOV, but that can also scale, so no different from quick move in that regard.

Also note that you can edit menu files and add shortcut keys to any command there, if you need quick access to frequently used commands.

If you don't need to see the object while moving, you can use non-visual move - MOVE - this command does not allow any kind of scaling, but it is a bit harder to see what you are doing when using it.

Yes. Well, CC2 files actually, but they are fully compatible with CC3.

Since what you are looking for are essentially just simple markers, if you don't find what you are looking for elsewhere, you can easily just draw them yourself and define them as a symbol. See page 75 of the user manaul that shows step by step how to make a basic symbol marker like this (Or page 105 of the latest published version of the Tome, if you have that)

Yes, you have to go through :ICON_CATALOG: to open it if it doesn't show up in the list of catalog settings, but once you click that button and get the Symbol Catalog dialog, you have two options, either find the .FSC file for the catalog (@Symbols\Cities\SS6\MS Color\SS6C_Ruins.FSC) and open that, which is the right approach and loads the actual catalog with all the symbol behavior, OR navigate all the way into the artwork directory (@Symbols\Cities\SS6\MS Color\Ruins) pick an image file, and hit ok, which is the non-optimal way, as it will just populate the symbol catalog window with the images in the folder without any symbol behavior like grouping, because all that is stored int he symbol catalog file.