Just a few general comments.
I don't use polylines / always explode them into lines, arc's, circles / basic elements.
I don't know about Autocad light. At one time it was a PITA if you got a light version and had to use the generated dxf in some other program or even within Autocad, but that was a long time ago.
The square, square with rounded corners were polylines, while the mitered square was a combination polyline and line ( which you could create as a single polyline if you wanted to) and the last one was individual elements. don't know if mixing them up creates any quirks in LazyCam.
Other than that the drafting looked ok ( just checked end points with units set to 4 places and not 2), no double lines, etc..
As far as Lazycam Mill goes, i just didn't have the energy to hack my way thru it. Fooled with it some and let it go, but, I had the option to use other purchased software. The turn part was enough hours spent.
Sorry, can't be of much more help,
RICH