Hi Jim,
To list the files, it would really depend how the tape was backed up,
for a tape written with tar
# tar tvf /dev/rmt/0m
fbackup
#frecover -I /tmp/indexfile -f /dev/rmt/0m
cpio
#cpio -itv < /dev/rmt/0m
The tape may not have been written with either of these as there are many other backup methods, these are commonly used however.
To reuse the tape make sure the tape isn't write protected and you can just overwrite it.
Clare