Thanks to Lucky9 for clearing up the USB flashdrive solution. I had set my vm to Fullscreen + Scaled and couldn't see Guest VM Menus to follow previous instructions; I couldn't locate a "devices" menu item anywhere.
I will continue to persue samba shares in a different thread.
A bazillion thank yous - mike
These are the instructions Lucky9 provided:
The OS window= the window that opens when you start an OS. It has a menu system at the top that concerns the VM that's running.
From left to right:
See the Devices for a list of available USB devices.
First: You need to insert the USB FlashDrive in the Host computer and then mount it.
Second: Open VirtualBox.
Third: Start the OS VM you want to use.
Fourth: Select the Devices menu.
Fifth: Hover over the USB Devices choice.
Six: Select the FlashDrive.
It will now be available. I use Thunar in this example.