Hello all,
In about 6 weeks I will be leaving for a year long travelling expedition across the world and I've bought myself a dji osmo action 3 with a load of mounts, with the idea of filming some nice scenes. Since I am pretty new to filming/action cameras I have been reading a lot about the camera, filming techniques, recommended settings and video editing. My plan is to record many different kind of clips and in the end compile it into some sort of 'aftermovie' using Davinci Resolve. So there will be high action footage, like mountainbiking, motorbiking, etc and more relaxed footage like hiking, snorkling, landscapes, city scenery, etc.

So far I've decided I want to film most of it in 4k 30 fps, except for some scenes that I'd like to have in slow motion, which are recommended to be filmed in 60 fps / 120 fps. So this is where some questions started to arise. I know there is a slowmotion mode on the osmo action 3, with the option to go 4x or 8x. But I also know there is an option to drag your clips out in the video editor, creating a slowmotion effect that way.
Question 1. What is the difference between these 2 methods, and which is generally recommended for the best results / quality of life?
Question 2. If I'd use the osmo action 3 slowmotion mode, in how much fps is that filmed and can I safely choose 4k?

Then I've heard that your 'project' in the video editor can only have one fps value. Let's say I go for method 2. I would like to combine my 30 fps footage with the 60 fps clips to get those slowmotion sequences in there. I've read that with the video editor you can convert the 30 fps clips into 60 fps, and that it duplicates the frames so that it ends up as 60 fps. This way you could take the actual 60 fps footage and slow it down to your liking, making sure it looks smooth and not choppy. And the actual 30 fps footage will still look the same.
Question 3. Is this a correct understanding of the subject? Am I missing anything?
Question 4. Is it also an option to set the project as 30 fps (to scale down on cpu usage) and convert the 60 fps frames down to 30 while still looking smooth in slowmotion?

Question 5. Related to the fps topic, we have the 25 and 30 fps standards for household lighting, which differ based on county/continent. For USA and lots of south american countries it is 30 (NTSC) and for Europe and most of Asia it is 25 (PAL). Is it possible to get a good workaround for this, so that I can combine my footage shot in NTSC and PAL countries, or am I forced to make 2 seperate projects to avoid the light flickering? I know there is an 'anti-flicker' option on the osmo action 3 with the option of going 50hz or 60 hz. But for me nothing seems to work to remove this. I am in Netherlands and have my setting at 30 fps, and my indoor lighting keeps flickering on my footage, no matter if I pick 50hz or 60hz...  

Thanks in advance for the help. I have most of my other settings down, but this particular subject keeps confusing me and I don't want to end up with a load of useless clips.
Looking forward to your perspectives!

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