Units change question.
I assume that when you refer to "boxes", you are talking about the Grid. The DSETTINGS command will open the Drafting Settings dialog. On the Snap and Grid tab, in the Grid spacing area, you could set the Grid X and Grid Y spacing to 1" and set Major line every to 12. Be aware that you have to be zoomed in far enough to actually see grid lines every inch; if you are zoomed out, the grid would become too dense to display. If the Adaptive grid toggle (in the Grid behavior area) is checked, the grid spacing will scale up, based on the current zoom; otherwise, the Grid will just turn off when zoomed too far out.
When I know how long I want an item (line, Wall, circle radius, etc.), I type the value in. If you are just looking for a rough idea of how the distance the cursor currently is from the previous point while in a command, you can set the Coordinates display to Relative (right click on the coordinates panel at the left end of the Status Bar, and choose Relative from the context menu, if it is not already the active choice) or you can activate Dynamic Input, specifically Enabling Dimension Input where possible, as shown in the image below. The coordinates display is just for looking; Dynamic Input will accept keyboard entry in the active dimension box (press the TAB key to cycle between the available dimension boxes).
