I confess I don't understand what you are trying to do, but for the sake of starting you off...
For nearly 10 years I have been using Debut for screen-capturing live wildlife cams 24/7, it's set to stop/restart every hour. I almost always record in .mp4, the files are smaller than .avi but I don't notice much, if any, difference in quality. I have never taken a chance on Fast Capture so I can't advise on that. I scan the finished 1-hour files in an editor and extract clips of interest and join them up, then upload to YouTube for sharing with the general public.
If you are recording a screen then the monitor resolution will affect the size of the resulting files, no matter what format you have set. Screen-capturing a 4K screen will result in very large files which are more cumbersome to edit.
You are talking about "home movies" so I presume you want your recordings made on a Windows PC to be compatible with iOS and Android - I don't think this is possible, but maybe someone here will educate us (me!) 🙂