DVD/CD Drive Physical Testing Software

I have a Dell Inspiron 6000 laptop PC with the following Sony DVD/CD Drive:
(All details copy/pasted from analysis of PC by Everest Home Edition.)
Device Description SONY DVD+-RW DW-D56A
Device Type DVD+RW/DVD-RW
Interface ATAPI
Writing Speeds
DVD+R9 Dual Layer 2.4x
DVD+R 8x
DVD+RW 8x
DVD-R 4x
DVD-RW 4x
CD-R 24x
CD-RW 10x
Reading Speeds
DVD-ROM 8x
CD-ROM 24x
Device Manufacturer
Company Name Sony Electronics Inc.
Product Information http://www.sonyburners.com/products/index.php
Firmware Download http://sony.storagesupport.com/dvdrw/firmware.htm .

The DVD/CD Drive has been giving intermittent problems with reading both CD & DVD media, and hardly ever writes. I have used a CD incorporating a lens cleaning device, but there was no improvement. Before I decide to install a new drive, I feel it would be a good idea to check/analyse by means of some available software whether there is anything physically/electronically wrong with the components of the drive.
a/ Is there any such software to check out the drive? Would it require a test DVD/CD (which could be cut on another PC)?
b/ Being a newbie, may I have advice on how to check the current installed software driver for the drive, and the procedure on how exactly to download and install any new driver? The driver has never been updated; I bought this PC in May 2005.
c/ If the physical drive needs to be changed, can I install any suitable make/model of drive, or must I get one from Dell only?
d/ If another suitable DVD/CD drive can be fitted, which make/model would you recommend?

Thanks in advance to whoever replies.

Cheers!