Natural selection does not care one bit about the individual, to the question is completely meaningless. Add to that, that we share 99.9% of our DNA, so you passing it on, means I'm passing it on for free, while you sit there with all the cost. Who's the fool now?! ;)

Potentially. You're mixing "fitness" with "intelligence" -- there's no guarantee that "intelligence" will guarantee fitness.

If you fail to achieve goals, you're not smarter.

But passing on genes is a pretty arbitrary goal. It's the one encoded in our genes, but (looks around at random object) passing on teacup design is encoded in a teacup. The most teacups are the ones that make people look at them and say "I want a copy of that cup". It's just statistics, not the ultimate meaning of the universe. The humans who think it's the ultimate meaning of the universe may be more likely to replicate - but that's a genetically inherited delusion, not a fact. You can pass on your editor choice just as well as you can pass on your genes.

What does the individual get out of passing on their genetics?

That depends on whether or not you value passing on your genetics.

Is intelligence correlated with having kids?

Are you implying homosexuals et al are somehow inherently dumber?