The gerber plotter does only allow you do print silkscreen for ALL components or for NONE.
If you want the DB9 connector without silkscreen you have to edit the footprint with the footprint editor and switch those silkscreen lines to invisible or delete them.
That’s why most people - after a while - start to run their own libraries
As for the Edge Layer (Edge Cuts)… if you SELECT it, it will be in an EXTRA .GML or .GM1 file (that’s the mechanical layer or one of them if you have more than one). If you DESELECT the option it will be in all of the layers you have plotted (.GBT, .GBL, etc… pp) and NO extra mechanical layer file will be plotted.
From my own experience Elecrow is OK with the Edge Cuts being on a separate layer and that one being called .GBR.
The settings I used for exporting the gerbers for ELECROW - I did not have any non-plated-holes (NPTH) though:
plot format: gerber
B.Paste (for stencil)
F.Paste (for stencil)
Exclude PCB edge layer from other layers
Use Protel filename extensions
Include extended attributes
default line width (mm):
drill map file format:
drill file options:
none (DESELECT merging of PTH and NPTH)