Copy move an object with cursors

Thanks,
I know this methode, but because I saw the plus sign and it did stay visible when I move the object the question came up…

Also like, to know how to adjust even more precise. My guess is that it, using the cursor keys jumps 2-3 points.

If I want to adjust a line bij 0,5 point its way to much effort to get this done by using the mouse.