Why Do Rich People Get Even More Rich?

I think you're absolutely correct to sum it up as "opportunity". When people complained that "Occupy" lacked a coherent message, I would say "the Tea Party connotations that through taxes and regulation the government curtails the liberty part of "life, liberty, and the pursuit of happiness", Occupy feels their right to an opportunity to pursue happiness has been taken away."

I'd actually guess (and bust a guess) that issues 1 and 3 are bigger deals than 2, though I think they all apply. For the third, I'm reminded of the British documentary series "7 Up", where 7 year olds were asked what they wanted to be, and what they wanted in life. Every seven years the documentary creators caught up with the people to see where they were. The three young white boys from well off families even predicted their lives largely. From their universities to one even serving in government. It was kind of creepy.

Compound interest is a strange omission from such an article.