What codec to use for render ?

Hi, I’ve got a problem. I use GoPro Hero 5 to film. Output quality in 4K from camera is really fine and crisp (use protune for maximally raw footage). So till this step everything is fine. But When I do some color correction and Color grading I render a video to 4K 60mbps. And after the rendering process while I’m watching a video the quality is so bad. I see some pixelated screen, for example the branches are full and entire video looks not as Good as it should be. I was rendering in h264 and now I that is not Good codec. Because I’ve got PC i started rendering in DNxHQ. Now the output video looks fine but for example on GoPro YT channel it looks way way better (I now that the are doing really professional color grading but I’m not about colors. I’m about that it looks more to DSLR cam than action cam). I also heared about Cineform transcoding and does it have any sense.  So to compress this text here are some questions I want to ask:

-is DNxHQ similar to ProRes 422 and with one is ”bigger” and better quality?

-what should I do to make this video more looks like DSLR?

-in sequence settings what editing mode should I use (now I use RED cam, but maybe there is something better)?

-why after color grading this video looks that bad?

-does transcoding to CineForm make any sense to have better output quality?

-does the power of computer affect to output quality or it jus changing the time of render?

-just what should I do (no the color correct or grading I know that) to make my video look similar to videos on YT gopro channel?

-does CUDA acceleration affect to quality on output?

So if someone survived to this moment I‘ll be thankful for any answer and tip.

Thanks