I agree with @HMG --CX wheels are weird. My thoughts:
After riding tubulars for years I switched to tubeless a few years ago and won’t be going back. I never thought gluing was all that arduous, but being able to switch tires mid-season is pretty nice.
I don’t think rim material matters all that much, except I would avoid thin walled aluminum. In CX you take multiple little rim strikes (rather than few large hits in MTB), so I would guess that thin aluminum would fatigue, but I’m not a materials engineer.
Wide wide wide. I’m running carbon rims at 23mm internal. Most tires that are branded 33mm set up around 35-36mm wide on these rims. I love that. That will happen more with tubeless vs tubulars. I had to buy special tires in 2019 that would only sit at 33mm wide on my rims so I could race cross nats.
I don’t think depth matters (my former triathlete-self just slapped me for typing that).
How muddy are your races? I’d go for quality, inexpensive, serviceable hubs. DT Swiss 350?