Since you have access to Bobcad, why don't you work your way through the tutorials and read the help.
Bobcad does not create the toolpaths automatically upon importation of the file. You will have to do a bit more work than that
Typically, when you draw something in a straight CAD program, you draw the part itself. You might be drawing this in 2d or 3d. To use a program like Bobcad, you will end up drawing what we call an "offset toolpath". This will be likened to a series of contour lines that follow the outline of your part, at a fixed distance from your part contours. This distance will equal your cutter radius, plus any finish allowance.
Bobcad (up to version 18) has some functions that will simplify the drawing of some of these paths in special situations. These would include pocketing routines, which will create a toolpath to clean out or finish mill a straightwall pocket, with or without islands. Drawing a "skin" is also another method of creating a toolpath wireframe next to a 3d object (one where simultaneous moves in all 3 axis may be required.)
You mention how to differentiate between your rough blank and the finish profile. In Bobcad, you can use your imagination a bit and create a "pocket" on the outside of a part, and then create quick toolpaths to rough all the excess material away. However, if you choose to mill only the profile, then you can ignore (at some peril!) the outside dimensions of your rough blank, and just mill the final contour offsets. I say at some peril, because you may need to watch that all your Z plunges are carried out in a safe area, at a safe feedrate, because of the existence of material in the area outside your profile zone.
I don't know what your Rhino part looks like to give you a comparative answer of what the "extra lines" are about. Probably if you post a file (in dxf format), someone will render an explanation of what you are looking at for machining purposes.