You're biting off a lot for a video newbie...
1. Hi8 is not digital
2. The advice for capturing Hi8 above is good ONLY IF the camera has Firewire out (which MANY don't)
3. If the Hi8 doesn't have firewire out, then you have to "capture" the video the old-fashioned way: analog RCA out > capture card (which will be a project in and of itself)
4. If you can, you want to capture to avi (like said above)
5. Coloartist is right, 24-bit will work, but you'll have to resample down to 48 kHz first (do that BEFORE you even bring the audio into your video editor)
6. Syncing can be a BITCH if you've never done it before, but...
7. First sync the "head", meaning get the audio in sync near the start of the video/audio by slipping the a/v tracks
8. Then you need to sync the "tail" of the tracks because they WILL drift, especially if you originated on Hi8 analog tape. Syncing the tail is done like someone else described above, you don't "slip" the tracks anymore because that would screw up the head sync you did in the above step, this time you have to stretch or compress the audio track until you have sync at the tail. If done properly, the entire show should basically be in sync at that point (but that does assume an even drift, which isn't always the case when working with analog-captured video).
9. After you've done all of that, then you need to encode the video to MPEG2 and the audio to either AC3 (lossy) or PCM (lossless) formats
10. And finally, burn to DVD
That is going to be one hell of a project if you've done it before. Welcome to the world of video editing and encoding!