I just bought an external hard drive that's 1TB. I formatted my laptop and burned Linux to it. The thing is, I also use my hard drive for other things. Can I move these boot files into a custom folder? Or should I leave them alone?
I'm not sure why you would want to move the /boot stuff. It should be possible, but it would break a lot of fundamental assumptions in boot-related tools.
One common thing that people do is store /boot on a separate partition, in which case /boot/boot should be a symlink to '.' so that when the bootloader mounts that partition, it still can access files under /boot.
That actually related to the underlying question, "I also use my hard drive for other things", which sounds like you might want a separate partition for that. But it's hard to be sure without knowing exactly what youwant to do