Looks like you've got a good combination of tools there anyway. I've recently migrated to Resolve too, I like it (previously I was using pay software which was easier to use, but Resolve seems great.. needs a recent PC though). I'm using Windows though.
There's lots of info here, some is Linux or Windows specific, but some will apply to Mac:
Regarding screen recording, again I can only suggest from Windows experience, but it is available for Mac too: Techsmith Snagit. It's not free, but it is low-cost for what it is - about $50.
I use it every day, for screen captures (images or video, it does both) so it's good value if you think you'll be using it regularly. It doesn't do video editing, but does it's core functions well (including image/video store and retrieve, annotations etc - useful if you're taking hundreds of screenshots).
Other than that, the only other suggestion I can think of is lighting is worth thinking about, and a tripod or similar if you don't have a way to keep it stable.
A thing I keep forgetting is to set the camera to 'shutter priority' mode. That's important if you're using home lights/desklamps etc. Once you set that mode, you can set to 1/50th second or 1/60th second (depending on country) and it removes any banding.
I would have said that audio is important, but in recent years Youtube seems to do some cleaning up/audio levelling magic automatically, and sub-optimal recordings seem to improve a lot after uploading to Youtube. It's got so good that I don't bother with a mic any more, the in-built camera mic seems to be fine (unless you're some way away from it perhaps).
I have dabbled in video on and off. For the most part have used OneShot open source software https://www.openshot.org/download/ . Unfortunately I am an Linux operating system user. I did a quick peak at the website and didn't see Mac supported. The interface is fairly intuitive (I have not video experience). It seems the interface aligns ( same terminology) with other video editing software.
After a number of false starts, I am finally getting off my lazy rear end, to produce my first YouTube video, but apart from having a cheap Camcorder, a cheap iMac computer, and DaVinci resolve.
What other tools do I need or can find to do video's, I'd like to know how to do screen recording on my iMac, etc.
I would like to find out what resources are available.
If anyone is interested the first video I am doing is a 4 motor Z-Axis Auto Align upgrade for people that have a 3D printer with there bed moving in the Z-Axis.
Any tips you can pass on will be good. The video wont be complete until all of the parts arrive.