Art-wise:
forums.civfanatics.com/showthread.php?t=492821 (Although, I find this tutorial to be a bit dated, most icons now look much better but these are essentially the basics and everyting).
Dated though it may be, the icons come out looking
exactly like base-game Firaxis icons, right down to the letter. I know that Colonialist Legacies and a few other series of civs take quite a few deviations from the Firaxis format, but that's their choice, and, to be honest, as long as the icons have some nice shadows and pretty lighting, people aren't really too picky about them, design-wise. All that said, should you follow the tutorial, you should have an awesome-looking icon in maybe 45 minutes on your first go. It's a great tutorial. =)
As for your file-creating error - whenever SDK refuses to make a solution for me, I go to make a new file again and ignore all of the prompts to enter titles and names and authors and special thanks along the way, leaving either the defaults in the boxes or a small string of random letters (to meet the occasional length requirements). For some reason, this always works for me. Lord knows why.
EDIT: Forgot to mention that I disagree that most icons now look much better. I, for one, quite prefer the Irkalla/Firaxis look. It's nice and simple.
...I'll shut up now, I promise.