How can I import songs from my Flash Drive to computer like I would from a CD?

The CDs are already at a higher quality. The files on the flash drive are just files. All you can do is copy them as they are. If you go back later and convert them to a higher bit rate, it can't change what the file was to begin with. Lower bit rates are more compressed, which means there is coding actually deleted from the files. You can't put it back once it's gone.