As far as capture is concerned, the primary format and method in Vegas is DV via firewire. Vegas can also control some TV tuner cards that have analog inputs, but files captured via that method are not true full-res DV. Just exactly what means of capture may work with your device is difficult to predict, based upon the supplied information. But I'd guess that you're looking at an uphill battle. It may be to your advantage to attempt to transfer the files directly, rather than trying a capture scheme. I did this with my Fujifilm camera by reading the data into my PC directly from the memory card, rather than trying a capture. (since there was no way to do it, anyway...)

As you know, there are some still cameras that can shoot a little video, and many camcorders that can take stills. Generally, these extra capabilities are for low-demand situations and not where top quality can be expected. Camcorders do videos best and still cameras do stills best.

You may be able to pull this off. I managed it with really crappy, low-res video from my still camera. If the video is important enough to you, it's worth the effort, despite poor quality. But I wouldn't look to this a good methodology if you're planning to document your family over the next 20 years.