Ken, as to drawing the angled side with un-beveled ends, you could do a couple of things. One of them is to utilize SketchUp's inferencing like this:
Guidelines mark the location of the outside of the board at the top and bottom. Use the Line tool and connect them as shown.
Move the cursor back along the line you just drew.
Don't click. Hold it there for two seconds.
Move the cursor up in the general direction of the next line and look for it to turn magenta and the Perpendicular message to appear. Let go of the mouse, type the distance (.75 in this case) and hit Enter.
Move the cursor over the long line again for two seconds.
Then move the cursor until the line turns magenta and you get the Parallel message. This time press and hold Shift to lock the line direction and move the cursor down until it snaps to the edge of the bottom panel.
Repeat the process for the perpendicular edge at the bottom. Hide the trim piece before you get started to make it easier to see what you are doing. Complete the face and you are ready for Push/Pull.
I can think of several other ways to approach this, too but I think this is a good lesson to learn. The inferencing stuff really is quite fundamental. Knowing how to use it will make drawing, especially drawing accurately, much easier.