DOC: depth of cut. This has two contexts: the axial length of tool engaged in the material, and the radial engagement (which roughly corresponds in your toolpath generation as stepover). If not qualified, it is usually axial, with the radial specified by as a percent of the diameter rather than a measure (even though the path generation wants the measure). For example, if I just drop Z by 0.100", my axial depth of cut is 0.100". If I don’t change Z, but move the position (x-y) into the material 0.030", then my radial depth of cut is 0.030". For a 0.125" tool, this would be 24% engagement (24% of the diameter of the tool is in the work) The Carbide3d chart doesn’t separate these, but at the top of this page, @ApolloCrowe states that they are for 100% engagement, meaning the radial depth of cut is the tool diameter, and the chart refers to axial.
Plunge and feed are in distance/min. I believe the chart on the carbide3d site is inches per minute.