I also noticed that the Youtube version looks quite a bit 'duller' and the drohne shots got a green-tint then what I get playing the local file on my OLED TV. Not sure whether its compression or just not the best export settings in Davinci Resolve. It was my first project I did start-to-end in Davinci, so still learning...
I have had the same problem. There isn't much you can do about YouTube compression but I have noticed that if you set your data levels to auto in the deliver page (Advanced settings dropdown) when exporting H264 it appears to compress the video levels down to 16-235 so I now always set the data levels to Full so as to maintain 0-255. I don't know if YouTube knocks the levels back down again during processing but I do notice a more punchier looking output at full data levels.
I have the 12-35mm and find that it works really well behind the 6" Dome. But I find that I generally opt for the 7-14mm more often than not when I want to shoot wide.
If you only have the dome port it is possible to do some semi-macro with the 12-35mm if shoot 4K and deliver HD with some re-framing. I also have the Olympus 12-50mm but I find that it doesn't really perform that well behind the dome.