How is it that evolution is so intelligent...
How is it that evolution is so intelligent that it could choose what species needs to evolve more, what not, what should evolve to be food for others and so on? Such diversity?
Evolution is not intelligent. There is no will or intelligence behind it, no decision-making of any kind. Evolution is simply the word we use to describe an observed phenomenon, like the weather.
Evolution, at its core, is an incredibly simple idea: the species most suited to survival and reproduction will survive, and reproduce. As far as how adaptations develop at all, those are the result of small, incremental and *natural* changes or mutations in an individual's DNA. DNA actually mutates all the time. Usually, the mutation has no effect at all. Many times, it has a bad effect (for example, severe physical deformities). And very few times, it has a positive effect-- for example, it might make a bird's beak sharper, and therefor make it easier to crack nuts. Such a bird would have a slight advantage over its peers-- it could get to food faster, or get to food which the other birds couldn't eat. That bird would survive better than the others, and when it reproduced, it would pass on this new trait.
That's why evolution takes such a long time to work-- species accumulate the positive mutations at a slow rate, and only the mutations which increase their chances of survival are "selected". That is what is meant by "Natural Selection."
Over time, this leads to phenomenal physical changes, like reptiles slowly evolving into birds and mammals.
For your second question-- about evolving to be food for others-- no species evolves altruistically in this way. In fact, that is one of the ways which Charles Darwin himself said that Evolution could be disproved-- if there was ever a species which evolved purely to service another species (ie, as food), with no benefit to themselves whatsoever.
See, nature is selfish. An apple tree might create apples to eat-- but that is only so that the apple seeds can be dispersed, thereby ensuring more trees in more locations, and therefor ensuring against extinction.
Consider this: in all the 100 million (or more) species on the planet, there have never been one found with an adaptation which didn't benefit the species, at least at some point in its past. If such an adaptation could be found, it would dramatically reshape various concepts of biological evolution.