I’d say take the latest stable one, which atm is 4.0.3. they released their major rewrite(version 4) a few months ago, but for now they still support version 3. Considering you are starting from scratch i’d say just go for 4. I have never used their tutorials myself (went about with only the public docs, and looking at other projects), but they have an entire page dedicated to it https://docs.godotengine.org/en/stable/community/tutorials.html. Feel free to take any one there.
Considering you have a low end pc i’d recommend trying godot. As someone who has been in the gamejam scenes for few years now I have seen it be used more and more. It is not the most powerful engine, especially compared to unity and unreal. It however is by far the easiest both on user experience and on computer resources. As a bonus it is fully free and open source, which is always nice. For the learning part I’d recommend just starting, being bad at something is the first step in being kinda good at something (this is a quote from somewhere, and i dont remember from where). Good luck!
I’d say around 1 time a week. I guess it just tends to happen with a lot of devs working on a single project. But we do have a daily rebase policy for all development branches, so I can’t remember the last time it wasnt some includes mixing badly, or a file being moved. These are all easily fixed.