I you are sinking in the swamp, you should get out of there right now.
Other computer, other operating system, new installation, whatever it takes.
Once you have it running on a different computer, perhaps with Windows, you could try installing Ubuntu on that computer, or using a USB stick with Ubuntu.
The link to the thread of the Arduino only working as root is from 2008. And I think I can remember I had to run Arduino as root a few years ago. So please forget that.
I you are sinking in the swamp, you should get out of there right now.
I know! That's exactly what I'll do. For now sudo should do the trick, but I want to minimize using sudo as much as possible.
I'll reinstall Ubuntu and see where that gets me (Windows is just too horrible an OS, so there is no way I'm going there). I just need to do this carefully, making sure not to screw up settings and files from other apps... It's just, I was hoping to be able to circumvent this...