1 - It is marginally more complicated than deleting the 2 files, since the gzip file gets expanded to a directory, you must delete the FFP directory as well as the fun_plug script.
2 - This is your Raid 1 mount "/dev/md0 on /mnt/HD_a2 type ext3 (rw)" and these are the remaining non-raid space "/dev/sda4 on /mnt/HD_a4 type ext3 (rw)" and "/dev/sdb4 on /mnt/HD_b4 type ext3 (rw)". All are ext3.