1. There was in fact agriculture going on for quite some time in various parts of the world before people in Mesopotamia decided to make it a full time job. Before that, people grew gardens and cultivated naturally occurring plants, which added but a few hours to a very light workweek. Totalitarian agriculture, on the other hand, caused food production to be the single most laborious and time-consuming task humans have ever come up with.
2. "The noble savage" or other variations which I have heard, basically endows hunter gatherers (and early horticulturalists) with ideal lives, unaffected by war, conflict, or disagreement. There is no basis for this opinion! There were wars, although they were very small in scale and were intended only as a means of defining a tribe's boundaries and a show of strength, rather than as an attempt to wipe out or take over a neighboring tribe. There were conflicts, and the means of dealing with them, much as there are among modern hunter-gatherers. Laws were not needed, because each culture had means of dealing with specific problems that worked, usually through recompense or restoration rather than punishment. In short, while there are many aspects of the ancient hunter-gatherer lifestyle we could stand to learn from, they were still human, and like any other animal, still had conflicts and obstacles. They also did not have access to all the wonderful things that science has brought us in the way of medicine and knowledge of our world and universe, among others.
3. They were slow/stupid/unsophisticated. I get really riled about this one. Some ancient peoples made remarkable tools with limited technology, incredibly intricate carvings, and textiles to rival the modern Italian fashion industry. They had the same brains we do, and would have had geniuses on par with Einstein, Beethoven, or Hawking. What they did not have was the 200,000 years of progressing knowledge to build upon as we do- they were the ones that started that knowledge base for us. The scientific method(In short: observe, hypothesize, test, repeat) was vital to early humans for survival. They needed to predict seasonal shifts, determine patterns and variables in animal migrations and plant growth, not to mention the extensive knowledge of animals' anatomy and behaviour neccessary to effectively hunt and use said animals. We are not the strongest, nor the fastest, nor the most agile of creatures, but we are the only ones with an ingrained desire to know what is going to happen and when!
4. They were 'closer to nature'. They were not 'closer' to nature, they were PART of nature. Humans didn't start looking at themselves as 'above' nature until we were so completely dependent on agriculture that we couldn't live without it.
I think that's all for now, but I'm sure I'll get back to the topic fairly soon.