Anyway, cart before horse: can somebody explain (and/or point me to links explaining) what rendering and dithering are and (more importantly) how they affect final sound?
Rendering is just the language WaveLab uses to describe the process of applying edits to a file.
As for dither, first it's important to understand
analog-to-digital conversion and vice versa.
Dithering is a process by which one converts a file from 24-bit to 16-bit. There's a
decent blurb on Wikipedia that explains audio dither pretty plainly.
Different editing applications may also employ noise shaping as part of their dither funcions. Noise shaping is a way of shifting the (basically) random noise produce by dither to certain frequencies the listener finds more desirable, usually higher into the frequency range.
Bottom line is a 16-bit file properly dithered from 24-bit will sound better than a 16-bit file truncated from 24-bit. And different dither algorithms sound better to some people than others. I performed a
dither comparison for my own purposes, and shared the results with others. You may not find it super useful, though, since if I recall correctly, divamum, you're often recording unamplified voice. IME, selecting different dither algorithms will have more of an effect on your recordings than someone recording from a PA. The reason is because your recordings will have more dynamic range. The (good) noise introduced by dither therefore will be more noticeable since your signal at times will drop to far softer than one produced recording a PA. This will make the dither you use, and the noise shaping options you select, more noticeable.
That said, probably none of the dither options in my comp will sound -bad-, but you may find you prefer one over another. I'd first start out getting familiar with the overall process of converting 24-bit files to 16-bit, and then start playing around with dither.
What software do you plan to use? While the general process steps are the same regardless of software - edit first (compression, gain changes, EQ, fading, etc.), then resample, then dither - different software uses different workflow to accomplish these actions. I've written a
24-bit workflow for Audacity. I'm also familiar with Cool Edit Pro / Adobe Audition, and
David Klein provided some really good informal feedback about its workflow when I first switched to 24-bit. If you let us know what s/w you're using, someone can probably provide info on proper workflow within the s/w.