1/ No the same removable device doesn't always receive the same /dev/sdX.If you
unmount it ( umount /dev/sdX) and plug it again, it can be called /dev/sdY (I
suppose the kernel keeps tne name in memory for some time).
2/ use "mount" without arguments., plug your flash drive and run "mount" again:
the new /dev/sdX (or /dev/sdXn) is your drive (or mounted partition). Unmount
it with "umount /dev/sdX(n)" and run dd with "dd if=input-image of=/dev/sdX
[options]" without the partition number if there was one. All this as root of
Good luck. Jacques