Anybody knows how to define drawing path in the part file so we can open part's drawing immediately from the part. And how we can include the drawing file name in the BOM in a way that it populates automatically.
Right click and select "Open Drawing". SOLIDWORKS looks for a drawing with the same name as the model, in the same folder as the model. If the drawing exists, it opens automatically. If such a drawing is not found, a browse window appears so you can locate a drawing manually.
There is no direct way for your other question. You can add a property say "Drawing Name" in the part/assembly properties and assign it a value. Then you can have the BOM populate that value.