I want to create my own audio CD. Should I render WAV files to 16 bit or 24 bit depth?
Audio CDs are encoded with 16-bit values. Higher bitrates are generally used for editing, not for playback. You can write 24-bit WAV files to an optical disc, of course, but it will not be a standards complying audio CD.
Presuming you are mixing/mastering 24bit (as you should be) I would create a 24bit master & then create a 16bit AudioCD version, dithered down from the 24 bit