So I looked on my iPhone and just to clarify, the edges of your background-image don't display, yes?
From my initial observation it has something do with the size of your background. Your width exceeds your height, which is most likely causing this issue.
And it's hard to master!
Does the air guitar count?
That's great to hear! Whether it's going into another field or continuing with your computer studies, all the more power to ya!
At least you have some computer skills to back yourself up if there's a time of need!
There is something to be said about the comic book industry. Prehaps you might want to open up a comic book store, hobby store or even start to actually draw and/or design your own comics. Writing comics and stories might also be a passion you can pursue and of course, there's just about a degree (or a related-degree) for almost everything! XD
Facebook and Twitter are great to drive traffic to your website, but Google+ (from some speculations) actually will increase your page rank in Google.
If you use an automatic translation, like Google Translate, you may be going against Google Webmaster guidelines. Here's an interesting article from MOZ that you may want to take a look at if you're considering using different languages on your site: http://moz.com/ugc/beyond-seo-why-good-translation-is-the-secret-sauce-for-successful-international-projects
The only thing I've seen between the two phones (which stands out to be prominent) is the fingerprint recognition on the 5s. I think the what's actually making the big difference here is iOS7. Personally, I'll stick with my 4s for now.
I may have some ideas for you, but it all depends on what you're capable of doing. What is your major and secondly, do you HAVE to develop the idea from scratch?