Saves are backwards compatible within the same Major version (a save from v2.x.x will work in any future v2.x.x versions of the game)

Hi, as others have said, upgrading won’t lose your 2.x.x projects. There’s currently no builtin support for sharing/collaborating with friends, but if you press ctrl+shift+alt+o in the program it will open the location where the save files are stored. Each project is its own folder, so you could send a project folder to a friend if you want (or even set up a git repo in there I suppose if you want to collaborate more easily). Note that while sharing projects should be reasonably straightforward, sharing individual chips  is more complex as they may have dependencies on other chips, and also need to be referenced correctly in the project settings file. Hope that info helps!

How do most people make a cpu