Hy JD,
I went with the Z6 for two reasons, the first being the price and second the file size.
The kit price with FTZ and 24-70 is very attractive and you do not feel neutered when you leave the store.
The file size is optimal for my use and I remembrer some Leica engineers saying that 24mpx is the best compromise in 24x36 and that they won't go after more pixel in the M system.
Also, the Z6 sensor is the same tech as the Z7 (BSI cmos sensor) and it is just very very good. Less pixels is also less error in action and, in the case of the Z6, much better video. ISO are close to D5 level ; it is a true adventurer camera. The fact that the two Z are exactelly the same build made me jump (I would never have bought the Z6 if it was less rugged than the Z7). So, except if you want to print large walls,ISO 64 and massive cropping, the Z6 is as efficient IQ wize than the Z7.
I just seen the 50f1.8S review and yea, this one might join dady this summer.
An another review from a respectable man:
https://blog.kasson.com/nikon-z6-7/nikon-50-1-8-s-otus-55-on-z7-zony-55-on-a7riii/
As for WB and portrait, I never really trust cameras. I always build a custom WB on the spot or place a grey card somewhere in the frame that I clone out in post. That being said the only tricky situation might be mixed lightings, for example day light from a windows and incandescent. In this case, custom WB is mandatory imho. If you are not familiar with custom WB you might start to train. With time it became a reflex and you'll be confident with almost all scenarios.