Ok, I understand that you understand the basics of lines.
What I am looking for is the ability to set the length of a part of the line to an accurate length. Lets say I want the end (red) to the first mid-point (upper right hand corner) to be .25 inches. I cannot do that.
Well, yes you can, you just need to learn OG. Not just the Lines & Shapes inspector. Never say "can't" it truncates your own ability to find out how you can.
Have you used the grid, and played with it. I think not. From your examples, you have maybe the Major set, that's all. Go to the Canvas:Grid Inspector. Ok, you can't choose your unit of measure, it is set to inches. First choose the minimum unit, the integral building block for your diag (I chose 0.2 cm; you might choose 1/8 inch). Set that up in the Inspector. Play with it; you might chose major at 1 inch and Minor at 1/8; or 2 and 1/16th (which gives you 1/8 increments, each minor grid square). Whatever, bit notice you want the integral building block, the increments of your line lengths. Now snap to grid, and Align to Grid; choose Edges for now. Now choose everything on your canvas, and Align to Grid.
Now remember, you
are doing the drawing, not OG, and you are using OG
set up for what you want to draw. Use a magnification that is relevant to your line-object. View Rulers, notice the tracking on the Ruler as you draw.
Start drawing. Be careful to always place the start-, end- or mid-points on the Grid. If any of them do not automatically snap to grid, choose the point and Align to Grid. Given that you are using a scale, Major, and Minor that is meaningful to you, that you can easily compute in your head, you should be able to easily determine any line length, as you are drawing (I certainly do, all the time; I keep track of things like "I want three Magnets, so I want the width of this thing to be divisible by 2 producing an even result so it will Snap to Grid", which mind you, is a damn sight easier in metric).
At the magnification that is relevant for your object, you should be able to count the minor grid squares easily. If you have difficulty, keep track of your start/stop coordinates on the Rulers.
And really, for me anyway, it is no big deal to draw a separate line fragment (with no midpoints), checking the Lines and Shapes Inspector; then place that line fragment next to the line object; and draw the next step in the line object relative to the line fragment; then discard the line fragment.