Unable to Format or Burn a DVD-RW

Question

I just got a new Samsung Slim External DVD Writer, which according to the box is Mac compatible. But after inserting a blank DVD-RW, I tried to format it by creating a partition with Disk Utility and got a "Partition failed: insufficient privileges" error, even though I was in my admin account, the DVD drive was plugged in correctly and the DVD said "DVD-RW" on it.
BurnAgain FS wasn't detecting the DVD, so I believed I needed to format it first, as I've had to do after erasing with Disk Utility a CD-RW burning session that committed an error. So I selected the DVD drive in the left column, 1 Partition under Volume Scheme, gave it a name, format and size, then clicked on Partition twice.
After getting an error, I then tried to create a disk image and got an "Unable to create 'disk1.dmg.' not recognized."
Is it true I don't have to format the DVD first before writing files to it?
If not, how do I format it?
And how do I write files to it?
Here's the disk info shown on the bottom of DU:
Disk Description: TSSTcorp CDDVDW SE-S084C Media
Connection Bus : USB
Connection Type : External
USB Serial Number : SATASLIM0000105fb96
Total Capacity : 0 Bytes
Write Ability : Read Only (DVD-RW)
Capabilities : CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-R, DVD-RW, DVD-RAM, DVD+R, DVD+RW
Partition Scheme: Unformatted
Here's the disk info in the pop-up panel:
Name : TSSTcorp CDDVDW SE-S084C Media
Type : Disk
Disk Identifier : disk1
Media Name : TSSTcorp CDDVDW SE-S084C Media
Media Type : DVDROM
Connection Bus : USB
Connection Type : External
USB Serial Number : SATASLIM0000105fb96
Locked : Yes
Writable : No
Ejectable : Yes
Mac OS 9 Drivers Installed : No
DVDROM : Yes
Optical Media Type : Unknown
Location : External
Total Capacity : 0 Bytes
S.M.A.R.T. Status : Not Supported
Disk Number : 1
Partition Number : 0

Answer 1

Just thought I'd add that I've an old, very heavy, Samsung external USB/Firewire multi-drive. Mine was from LaCie (liked the weight). Needed firmware & software drivers, which LaCie supplied with an oversight application, to update them easily.
Even after all the tech stuff was set right, to get an application to recognize the drive (in its preferences), I would occasionally have to unplug the cable, then plug it in again; or not add a disc until requested by the burning program.
These kludges I got in the habit of using. The second often suffices.
PS. iMovie & iDVD are wonderful for quickly making DVDs. Free, Aqua interfaces on Linux commands allow making or copying of double- and dual-sided discs (which don't burn as fast). 'Burn' will make analog or digital (mpeg) audio, & basic. For more details about this very complicated subjects of VCDs, SVCDs, &c, see dedicated websites. Here's a safe one I can recommend:
Afterdawn (Finland)
http://www.afterdawn.com/
PS. If you have more time than discs, you might like to create a virtual disc on your hard drive, as I often do, then test it well before actually burning & verifying it. (I burn at full speed. Never a problem with Verbatim or Taiyo Yuden media.)