1)  Non-human animals have less developed brains than humans.  Among humans, it's possible that practical realism might be more adaptive than factual realism.  People who have certain delusions might be better adapted to get more power, money, sex, etc. 

2)  Humans don't have an "essence."  Humans can be defined biologically.

3)  Ask a biologist.

4)  Evil is adaptive.  People who are evil can get what they want from the weak.  This will backfire on the evil person if they don't balance their evil with good, because unfortunately for the evil person, people catch on pretty quick.  Evil people usually end up banished, beaten, imprisoned, or murdered.  There is a point when evil becomes disadvantageous, and that is when there is so much evil in a society that the evil people eventually destroy each other.  People who work in groups are more powerful than individuals, and that is why good is more common than evil. 

5)  Limited resources, a growing population, and limited space.  Organisms will compete for the resources, and some will get them and others won't.  The traits that allow the organisms to get the resources come from genes, and those genes will be passed along to the offspring, provided one of the resources obtained was sex.  The limited resources and growing population causes a competitive environment and a predator vs. prey dynamic.  Also, don't forget that random gene mutation causes variation.

6)  Four stones, but you have to put the fourth stone on top of the other three so it makes a little cone.

7)  Macroevolution has been observed in the lab and in nature -- another word for this is speciation.

8)  I don't know of any evidence that the laws of nature have changed or could change, but I'm not worried.  The laws have such regularity that I have no reason to think that they will change.

9)  In a world which was designed by an all-powerful, all-knowing being, evolution could be false if the being eliminated gene mutations, the possibility of interspecies breeding, or reproduction altogether. 

10)  Yes.  Evidence of evolution lies in the fact that copying errors take place in genes and that organisms that have certain traits get what they need to survive and reproduce.

Arbitrary statement. Is rationality the greatest tool for the survival of any species? Like every other attribute that a species can possess that depends on environment and ecological niche within that environment.

In any case, rationality is fairly well distributed. One simple way of illustrating that point is that we can model the behaviour of most species quite accurately on a computer, so it must obey mathematical rules. 

See the definition of the word Species and the Human Genome.

Nonsensical question. If you began making the neccesary changes you would cease to be yourself long before you ceased to be human.

Both are manmade constructs. Evolution has nothing to do with their existence.

Chemistry.

The Sorites Paradox, only with stones instead of sand. People have been studying that for two and a half millenia. Wikipedia gives quite a good introduction. Why is that relevant?

Has been observed, look up the London Tube Mosquitos for just one example. There is also plenty of evidence in the fossil record. Also, distinguishing between macroevolution and microevolution is a false dichotomy.

'Does nature evolve?' is nonsensical. The laws of nature do not evolve - what would there be for them to compete with or for? If you meant to ask, do the laws of nature change the answer is no, at least not measurably in the last four billion years.

Sure, if they were lifeless.

Fossil record, observed speciation, observed evolution of behaviour and physical characteristics within species, endogenous retroviruses, biochemical similarities between certain species, chromosome configuration within various clades, mitochondria...

agreeing with all the other answers, here is my two cents:

Is it the greatest tool for survival? I would venture to say that our reptile instincts are the greatest tool for survival. Or maybe it's the ability to reproduce, which is why we are here to begin with.

Too broad of a question. Perhaps the ability of higher order thought. But theoretically, this could be achieved in another arbitrary species and furthermore we do not know if other mammals are not capable of higher order thought--we cannot ask them.

um, strange question. You would have to become another species.]

Evil is a by-product of other processes that assisted us in survival, such as selfishness and xenophobia. Survival itself creates a propensity to dominate others, which leads to corruption and evil. Someone suggested The Lucifer Principle. Read it.

Life.

A pile suggests plurality, so I say 2. What is the point of this question?

Fossil record. It has been tested as well. And observed. There are fish living deep in the ocean that have not evolved for hundreds of millions of years. Also, the rapidly growing field of genetics gives a rich treasure-trove of evidence. Read some Richard Dawkins. In fact, read The Origin of Species

Nature does not evolve, how could it? If the laws of nature mutated and changed, then we would not be able to make any of the observations we have made, and likely we would not exist.

The key word here is possible. Of course it could be possible, but highly speculative to the point of fiction. It would require life unlike anything we know, and possible a whole different set of natural laws--not our universe.

Okay, this is just a really silly question. Do some research.

Is it just me, or is "essence" a remnant of platonic philosophy that needs to be flushed down the toilet of philosophy with all other outdated concepts?

Not necessarily. It is sometimes a vague concept which attempts to describe the "core" of a hierarchy of "emergent energies" (in the biological context) that in sum total constitutes the entity "man". Unless you want to define the human being as a "thing" - which is truly an outdated concept - we have to study her as a process that begins in conception and ends in death and decomposition. In this context, "essence" means the subjective principle, the feeling of being alive and separated from the world at large.

"Essence" is an attempt to capture the feeling that there is some constant core 'thing' that unifies what we perceive as an otherwise non-constant 'entity', such as a particular individual human being, or another living creature, or a cohesive group of people (tribe, nation, ethnicity, etc), and so on. As distinct from, say, a rock or other dead physical object, which does not appear to change perceptibly in our life-time.

It is illusory when it inspires the thinker to ascribe it some quasi-pysical reality in itself, whereas it is really just a label we put on the fact that we can identify a strong thread of continuity or connection through time of what is, in each case, a continually changing assemblage of elements, be they atoms or individuals.

 'Scuse me for barging - but, as an aside, I think you need to give early humans a little more credit for discerning between a Glargax and a rock.  

However, I get the jist of your suggestion - that the difference between an animated object and a non-animated object may have prompted a belief in a soul (essence?)  Witnessing the sudden abscence of animation is bound to be cause for.... concern? curiosity?  distress? (divorce!?)

Many early cultures believed animals had "essences" or "souls" as well as humans.  I think the belief that humans only are in possesion of a soul, is a relatively recent mindset. 

I don't recall positing that early humans believed only humans had souls.