I'm sorry if this sounds a bit noobish, cos I'm not too educated with DVD/CD burning technicalties, but what's with the different writing modes (e.g. CAV, CLV, P-CAV, P-CLV, Z-CAV, Z-CLV, etc...)

Are certain modes better than others? Perhaps in terms of burn quality? Speed?

CAV/P-CAV modes are faster than Zone-CLV for the same writing speed, but the non-fixed speed makes calibration more difficult.

CD-R started at CLV (evolving from audio at CLV 1x)
As speeds crossed 16x or so, the CD could no longer be spun fast enough at the inner zone to be CLV, so then it starts out rotationally limited, and then:
1. Zone-CLV - holds transfer rate consatant, RPM falls, until it stops and steps the RPM up, and continues at the next speed - this may be one step, two steps, or more.
2. CAV - Holds RPM constant, transfer rate increases througout.
3. P-CAV - As CAV, until the transfer rate reaches the maximum or target value, then proceeds as CLV with constant transfer rate and falling RPM

For audio CD on modern media, playability may be more consistent at the highest CLV speed of the recording drive (typically 16x) as the characteristics of the burn should remain constant throughout - lower may be better, but modern drives and media are not tuned for low speeds ... the "sweet spot" for CD-R is normally two or three speeds below the maximum for drive and media.

As for P-CAV/Zone-CLV - not much in it - some drives switch for different media types, though the push is towards the inherently quicker CAV/P-CAV mode if they can make it work.