I have the previous HD350 model, though it is very similar. I used a Lumagen HDQ to improve the colour gamut, though now I'm waiting on my VideoEQ Pro to arrive, so I've just backed the colour off to -10 and tint to -4. If you are getting clipping, you may just have the main contrast too high or it could depend on which colour temp mode you are using. I use a custom colour temp and use an i1 probe to measure and correct the greyscale using the RGB controls and the custom gamma controls to correct the gamma. Once this is set correctly, it might be easier to set the colour control to avoid clipping. However you will never get the colour correct on this model without an external device like the HDQ/VideoEQ Pro/Radiance, so I wouldn't get too hung up about it, just enjoy.
Zooming: Been there, done that, bought the lens...now using e-shift.