I've had good experience stitching parts together with handbrake. Honestly, it's much easier than importing to an editing suite (and getting the export settings right 😬).
Davinci resolve will allow you to do what you wish, just don't get intimidated by the interface, and look up the task you want on yt very straight forward and I only use 1/100th of its power
Sure, but if you install DR, then you have DR to do other things. Like chase that YouTuber dream, or field annoying calls from your great aunt who knows you can edit videos to digitize her parents super 8 family videos that are have rotten.
It is a program I have used to make bad tutorials and bad compilations (I have no skill hehe). It was a suggestion and maybe after doing this they may go deeper into video editing/making, or not. Like I said I barely make use of all its power, op will decide what they will do