There are many ways to do it, I would, add an skeletal mesh to the main character, spawn it behind your character as you said, every tick you set its location smoothly by using the function vinterpto the parameters are( the current companion location, your characters back location, get World delta seconds, a function that moves faster according to how far both characters are from each other, the further they are, the faster it should try to reach your character).
When you press shift you can do a lot of things, scale it from 0 to normal size, spawn it inmediatly by setting its visibility to true etc, it all depends in how you want it to look.
I’m a noob myself, but I’m working on a similar project. I could be wrong but I’ll answer as far as I understand so far.
i really don’t know. My plan was to create a completely separate character and have him follow much the same as an enemy would. That may work though for what you’re trying to do.
still working on that too. I would start with an enemy AI tutorial that teaches you how to make an enemy chase you, and then add mods too it. Probably something player character and get wold position and traces (blueprint nodes).
input action shift key and spawn the character in pressed and destroy on pressed again. Or something like that. I believe there is an alternator node in the same section as the branch node that would accomplish this.
This may not be helpful and you may know more that me, but I saw no one had replied yet, so maybe this will point you in the right direction if you haven’t solved it already.