Re: how to get quality outline from imported bitmap
The screenshot is too small to see what your problem is.
If you want to make a cad drawing (vector lines) of the bitmap you have trace (vectorize) it. LibreCAD has no built in tool for that. It can be done with Inkscape. Still the results may not be up to your expectations.
If you just want to display the bitmap in the drawing, and it seems not right, maybe something is wrong with the bitmap. I can't tell without further information. You may provide it here with More v - Upload a file for examination.