How do I remove or change components in an assembly without changing the existing detail numbers in the BOM, and is there a way to link the detail number on the individual drawings to the BOM?
Welcome to the forum. There is a button you can click for "Do not change item numbers" in the Item Numbers section of the PropertyManager for the BOM. I haven't personally used it, so I can't promise that it will do what you want, but as far as I know it's your only shot.
As far as linking numbers, if I understand you correctly, right-click on a drawing view, choose "Properties..." from the drop-down, then you can link the drawing view to a BOM in the Properties dialog box.
Retrieving data ...