I'm working on a project imported from my XH-A1 using Cineform HDV. In the project properties audio tab, the default sample rate is 44,100, and another default is 16 bit. Are there any advantages to changing these?

Ideally the project properties should match your source material.
Here's how to do it if you're not sure what those are.
Open the Properties window.
Click the folder icon ("Match Media Settings") to the far right of the Template box.
Browse to the folder where your clips are.
Click one of the clips and then click "Open".
The settings in the Project Properties window will now match your project.
Click "Apply".
If this is the only kind of raw footage you're dealing with, click the "Start all new projects with these settings" box and click "Apply" again.

Thanks! I assume that will match both video and audio settings, right?

You can't create information where there is none, however, 24 bit audio has more dynamic range than 16 bit audio. So, if you intend on processing your audio, it might pay to switch to 24 bit for the processing, then dither back to 16-bit for printing.

Okay, I tried the match media settings. The only thing it appears to change is the template selected. It made no changes to the other video or audio settings, even when I changed them and tried different ones.

In terms of 24 bit versus 16 bit - I intend to render the project, then open it in DVDA and made a DVD. Given that, is 24 bit better? What about the 44,100 setting versus the other options?