How to mount this USB hard disk?

Trying to mount a USB drive to use as a backup drive as the tape drive recently locked up.
Being a BSD noobx10 I am having a few problems that I hope someone can guide me through...

Existing mounts are:
/dev/ar0s1a on / (ufs, local)
devfs on /dev (devfs, local)
/dev/ar0s1e on /tmp (ufs, local, soft-updates)
/dev/ar0s1f on /usr (ufs, local, soft-updates, acls)
/dev/ar0s1d on /var (ufs, local, soft-updates)
devfs on /var/named/dev (devfs, local)


Plugged in the USB disk and checked dmesg which looks OK up to "bad FAT32"

umass0: Maxtor Corporation Maxtor 3200, rev 2.00/0.01, addr 2
da0 at umass-sim0 bus 0 target 0 lun 0
da0: <Maxtor 3200 0343> Fixed Direct Access SCSI-4 device
da0: 1.000MB/s transfers
da0: 152627MB (312581808 512 byte sectors: 255H 63S/T 19457C)
mountmsdosfs(): bad FAT32 filesystem                               <---------------What to do about this
mountmsdosfs(): bad FAT32 filesystem

------------------------------------------------------------------------------------------------------------
 camcontrol devlist
Password:
<Maxtor 3200 0343>                 at scbus0 target 0 lun 0 (da0,pass0)
-----------------------------------------------------------------------------------------------------------
Then I tried to mount

mount /dev/da0 /mnt/usbdisk
mount: /dev/da0 on /mnt/usbdisk: incorrect super block

Then I tried to specify the file type and got:
mount -t msdos /dev/da0 /mnt/usbdisk
msdosfs: /dev/da0: Invalid argument

-------------------------------------------------------------------------------------------------------------
Maybe I need to wipe the existing disk partitions before I mount it, so I explored with fdisk...

fdisk /dev/da0
******* Working on device /dev/da0 *******
parameters extracted from in-core disklabel are:
cylinders=19457 heads=255 sectors/track=63 (16065 blks/cyl)

Figures below won't work with BIOS for partitions not in cyl 1
parameters to be used for BIOS calculations are:
cylinders=19457 heads=255 sectors/track=63 (16065 blks/cyl)

Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
sysid 7 (0x07),(OS/2 HPFS, NTFS, QNX-2 (16 bit) or Advanced UNIX)
    start 63, size 312576642 (152625 Meg), flag 80 (active)
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 1023/ head 254/ sector 63
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
<UNUSED>
The data for partition 4 is:
<UNUSED>


Are ALL external USB disk drives /dev/da0?   I want to be certain that any changes I make are actually to the USB external hard disk.
What is the best way for me to mount the drive I have plugged in?  I think that I need to use fdisk, but that only provided a listing not a menu like I have used with Suse linux.

Please provide clear step by step instructions, ie BSD 101 style.