No, you won't earn more when premium users stream your music, I think it's the same amount. Signed artists will receive $0,0044 per stream, for unsigned artists this is $0,0038. I don't think the country matters.
That's interesting, I didn't know that! What do you mean by "signed" and "unsigned"? Signed to a major or signed to an independent label?
How does Spotify know who is signed and who is unsigned? If I release all my music through some small independent label and they upload it via a third party service to Spotify, would this be considered as a "signed artist"?