- just try to use or modprobe it and find out by trial and error
- see which filesystems modules are available: find /lib/modules/$(uname -r)/kernel/fs -name "*.ko"
- look in the config for your kernel to see if something is enabled: grep CONFIG_UFS_FS /boot/config-$(uname -r)
4) cat /proc/filesystems
UFS support (read-only) is avaiable in the centosplus kernel but not in the "normal" one. Switching kernel is not hard, yum install ... edit your grub.conf and reboot.
Yes.