There are USB video adaptors, but they provide an analogue video input, i.e. you will lose quality adn/or frames. You won't get digital transfer over USB - it simply doesn't have the bandwidth.
Best bet is to get a firewire card which you can plug your camccorder straight into. However, some people have found iMovie to be fussy about the low (50MHz) bus speeds of the pre-G3 Mac's. Do a search on these forums for more info.
Firewire cards can be had for £20/$30 so it's probably worth just biting the bullet, and seeing how it works for you.
You will need plenty of disk space for DV capture. Roughly 1GB per 5 minutes. I would really recommend using SCSI drives in your 9600.
Although ATA drives are cheaper and work fine with later Mac's, I'd recommend you keep the internal PCI bus as free as possible (i.e. dedicated to handling your DV) and instead attach a couple of SCSI drives to the internal SCSI of your 9600. Also, the SCSI drives don't have a cpu overhead like ATA drives can.
However, your mileage may vary. v8q seems to have no problem with ATA and DV.
You have plenty of room in the 9600 for additional drives, and the internal SCSI is preferable to the external - it's twice as fast. 68 pin UltraWide SCSI drives can be had fairly cheaply - £40 for 9GB here in the UK. You'll get close to 10MB/s sustained transfer with a decent UltraWide SCSI drive attached to the internal SCSI bus, which isb't far off what you get on recent Mac's, and more than adequate for DV...