if so do i need to change anything in the gameslist xml or anything else so the art shows up from the hdd
The gamelist.xml file has the relative path to all the images (and videos). Depending on where you moved/copied the boxart from, you'll probably need to edit every image path in gamelist.xml.
If you use something in Windows like the Universal XML Scraper to get all the images and it makes an gamelist.xml file for you and you can use that in your retropie-mount/roms/snes.
There are other ways to accomplish this but I'm not sure what the best would be for your setup.