So what are the requirements for these programs? Are there GPA averages, background, personality requirements? Or can I just fly over there present my GED and register for a semester?
No idea about your visa, but if you are enrolled somewhere that shouldn't be a problem.
Application process: will vary widely, for many human sciences you can just enroll (Sociology, History, Gender Studies, all that stuff). You might even be able to just enroll for Business in some places.
For CS degrees sometimes you have to apply formally and show what projects you have done, submit your grade sheet, sometimes interviews. For my M.Sc. I was allowed to interview via Skype because I was abroad at the time. They gave me proper coding and interview questions and grilled me for 45mins. Some proof of A-Levels will be required.
Living costs: Will vary depending on where you go. Berlin will be dead cheap, so will be many places in the former GDR, while southern cities like Munich or Stuttgart will be more expensive. Hamburg is also fairly expensive. Nothing like the Bay Area or NY though.
No idea about the other mentioned countries, but I was surprised that Scotland didn't show up, but they might be only free for non-english EU citizens.
Just get in contact with the admission officers. They will give you instructions on what you should do to become eligible. For example, they might request you to attend community college to get some credits such as Calc I to Calc III and give you a conditional offer. Once you get your credits you are admitted.
