You might want to work through Tutorial: How to make a footprint in KiCad 5.1.x (From scratch)?
Tldr: there is a user grid so no need to work with ridiculously small grids. (And the array feature)
Colors of elements are dependent on their layer (necessary in an ecad tool that uses 2d rendering to work on a 3d object)
Line widths are changed within the line properties dialog (right click properties or hotkey e). Defaults are in the preferences menu.
to set the origin after the footprint is done use the anchor tool (right toolbar, or place menu).