"Communism was supported by the dirt poor working class so they could get more money, they figured if everything was spread equally they would get more. Communism came about because of the greed. It didn't work out though."
I think it's more likely, from history, that Communism rose from the widespread oppression of a 'peasant' class - conditions in Tzarist Russia - from which a large portion of Communist theory came, were appalling - actual slavery - peasants were resources/objects/property. I think it quite rude, then, to suggest that the popular support was greed for money based - more likely greed for freedom. How disgusting.
"You don't own anything in communism. Everything belongs to the state. "
State and Communism are not one and the same.
In soviet russia, state was paramount, and very quickly became tyrannical. It was touted, however, as a democratic state based on communist ideals.
The breakdown of society in the USSR was not directly through communism however, but the usurpation of this democratic principle, which is one of the foundations of communism.
The outcome is just as it would be in the USA if this democratic principle broke down to the same degree - the communism aspect is entirely beside the point.
It's also fair to say that, in general, the everything does NOT belong to 'the state' but, rather, to EVERYONE.
These are the fundamental differences between Libertarianism and Communism - this vastly different emphasis between Individual and Community.
But these are only one aspect of the two philosophies - otherwise they maintain many similarities

just as 'low fat' 'high-carb' normal fat foods are pretty much the same bar a few key differences.
"Communism just can't work. It had more than a century to evolve - may I remind you that Karl Marx made his "Kommunistisches Manifest" in the 19th century? Communism didn't evolve to a better system, it evolved to a worse one (e.g. Cambodia). It failed and its time is over."
Just like in the USSR - and yet such abuses are not aspects inherant to Communism, but are, instead, of sociopathic and abusive individuals and governments.
"Communism depends on concentration of power to the government so that this government can transform a nation into a communist society. But when people gain so much power - they never give it back. "
Take a look at any country in the world, and this concentration will be evident to varying degrees - and yet not all of these countries would be considered Communist.
Ultimately, such a concentration of power is NOT a feature of Communism, but, rather, a feature of some societies - I am particularly aware that some Communist communities never resorted to force/power to become, or even maintain their Communism. Some, current communities remain, basically, Communist, and still have not utilised such a method.
"Those schools have names like "Mao tse-tung" and "Ernesto Guevara", and it´s needless to say they indoctrinate the kids more then Goebbels would have dreamed."
This is also an issue with other 'schools of thought' who promote other economics and ideals. It's nothing, really, to do with Communism, but with people who wish to manipulate children into their beliefs - I'm also of a mind of religious schools - and let's then discuss the murder of people on religious grounds shall we?
Ultimately, Communism is flawed, just as Libertarianism, and, actually, for the exact same reason.
The key is to keep an open mind, and, I think, to make something of a mix of all.