The fact that clear is started in the background, is reflected by the output:
The number between  is the shell's job number for the background process (run the "jobs" command to find any running jobs). The number at the end is the process ID. So yes, the second number (and sometimes the first one too) will definitely change.
You should give the system sufficient time to (un)mount the disks when you swap them. And the light should go on when you issue the dd command.
I found some tools related to working with DOS disks: see "man mtools" for details. Not sure if any of them actually checks DOS disks. Then again, "fsck -t msdos /etc/fd0" (or "fsck -t vfat /etc/fc0) might work too.
Normally, though, fsck will check the filesystem type automatically if it's set to "auto" in /etc/fstab.