Broadly speaking, it's fully backwards compatible with the Sound Blaster 2.0 (and by extension the original Sound Blaster). This then also makes it compatible with the Adlib sound card, since the Adlib also utilised the very same Yamaha OPL2 FM synthesis chip. However, take note that the Sound Blaster Pro 2 and later Sound Blaster models does utilise the Yamaha OPL3 FM synthesis chip (the YMF262), whereas the original Sound Blaster utilised the Yamaha OPL2 FM synthesis chip (the YM3812). From a gaming perspective, it makes no real difference, apart from the fact that the OPL3 is a stereo synthesis chip and has more channels, whereas the OPL2 is a mono synthesis chip. Therefore, later games that were written to make use of the OPL3 FM synthesis chip's stereo capabiltiies, will sound better on a Sound Blaster Pro 2 or later sound card.

The CT1600 is referred to as the Sound Blaster Pro 2, since you had an earlier revision (the Sound Blaster Pro 1) that utilised two OPL2 FM synthesis chips in order to produce stereo sound output. Some games, that were specifically written to make use of this, will not sound correct on the Sound Blaster Pro 2.

No Sound Blaster card was ever Windows Sound System compatible (unlike many clone manufacturers) since you require a specific CODEC chip (the most popular ones being the Analog Devices AD1845 and the Crystal Semiconductor CS4231A codecs, and their later variants). There was no reason for Creative Labs to have extended support beyond their own standard (since Sound Blaster was the de facto standard).

Thanks a lot!
BTW, do you know what the CT1600's maximum sample rate is? The VogonsWiki website says: unknown.
Also, regarding the CD-ROM interface, VogonsWiki says: Matsushita MKE. Is that also known as the Creative/Panasonic proprietory interface?
Finally, I think I read somewhere that Microsoft shipped drivers for the SBPro2, and if that is the case, then what is the difference between that level of support, and "WSS"? (I could be mistaken about this though, it's just a vague thought.)
Thanks.

EDIT:
Perhaps I am thinking of the Microsoft Windows multimedia extensions?
END EDIT.

22.05 kHz in stereo and 44.1 kHz in mono. Both is 8-bit only.
Yes, the CD-ROM interface on the CT1600 is the Matsushita MKE interface, which is the same as the Creative/Panasonic proprietory interface. There were other Sound Blaster Pro 2 models that also had the Sony & Mitsumi CD-ROM interfaces. Take note that, although the CD-ROM interface on the CT1600 looks like an IDE interface, it's not.

Under Windows, each hardware device (sound card) requires its own driver. Since it was a popular sound standard back then, it was just included with Windows. Windows was shipped with drivers for many different hardware devices.

Windows Sound System was actually a sound card released by Microsoft for, Windows 😊. But, it worked just as well under DOS, provided that the particular game or software had specific driver support for it.

I think there's more to WSS. It's a little murky because (from what I can tell) "Windows Sound System" describes:

1) A physical product, being the 16-bit reference sound card in a box with a mic and headphones.
2) A standard meant to coalesce software support to one driver framework, despite the fact there were already other standards that had gained significant market acceptance, and creating yet another "standard" just fragmented the market more.
3) A driver package (1.x) released by Microsoft that would work on any device that adhered to 2) above, including 1) above. However, they also released the 2.x series of drivers which added support for various 3rd party codecs (including Sound Blaster) to bring them into the Windows Sound System fold.

What could possibly not be clear about that convoluted heap of marketing? 🤣