Next question: What is the Communist view on green economy?
I assume you mean one which pollutes very little, and is based upon renewable energy? Wholehearted endorsement. While environmentalism may not have been at the forefront of the old socialist states' concerns, it occupies a central one today. The communist movement today bases its positions primarily upon long-term sustainability: of the economy, of the environment, of everything. This is something which makes me very happy, because I think it reflects a much more holistic and mature view than before.
I don't believe in communism as a realistic or, as for now, moral way to build a society, in a foreseeable future. It probably won't need to be actively fought since it's weak compared to other ideologies. Just look at the revolutions in the Middle East. --- just to come clean.
My questions as a communism ignorant:
Ah, these questions remind me of the good ol' days of Ask a Red! You warm my heart, young Loppan!
1. Where, what and when was the the most successful attempt at communism made?
Difficult question, since communism and socialism are not the same thing. Socialism is the process of turning capitalism into communism. It is when we dismantle capitalism and implement the policies which will take us toward communism. Communism is the stateless society of free equals, without private property or differences of wealth. Socialism, being the road which takes us there, still retains many of these things, although they are on their gradual way out the door.
However, it is almost universally understood that the best attempt at permanently departing from capitalism was the Paris Commune, in 1871. Marx himself wrote about it in The Civil War in France, a book which basically amounts to "see, THAT'S what I'm talking about!" However, their execution was no flawless (especially seeing as it only lasted a month) and numerous lessons were learned from it, which were implemented in 1917. Lenin wrote his own commentary on the Commune, which are today published together with Marx's.
2. Why does it always fail and what do you regard the largest hurdles for a successful and long lived communist state?
First, there is no such thing as a communist state. Communism is a stateless society. States are tools of class dictatorship, used for maintaining order in a society split into groups with irreconcilable interests. Since communism will be a society in which classes have been rendered impossible, the need for a state will wither and die, and there will only be government, which is responsible for everyday functions of administration, distribution, and arbitration.
There are myriad ideas as to why socialist states have "failed" to reach communism. The first is quite simply that they did not have enough time. Remember that socialism/communism are directly antithetical to capitalism, and their very existence is a challenge to the capitalist-structured society. For this reason, capitalist-ruled states have always sought to destroy this new and dangerous force. The same thing happened to Republican France; after removing the King and declaring a republic of all the people, all the monarchies in Europe turned France into a pariah, invading it with the expressed purpose of restoring the King to the throne and destroying this awful new idea which threatened their own power. As we know, they eventually succeeded. So it has been in the Soviet Union as well. But, as we also know, republicanism eventually triumphed across the world. I believe socialism will one day as well.
Other things to remember are also that the socialism which Marx and Engels spoke of, which would arise because of capitalism and inevitably replace it, has never actually happened yet. All the socialist revolutions have happened in infant industrial states, never mature capitalist ones. While I don't think it's necessary to wait until capitalism is "mature" in order for the working class to take charge, I do think it's worth remembering that things didn't exactly proceed as Marx envisioned. "It hasn't happened yet" isn't a fault in Marxism, though, it's a mere statement of fact. It doesn't mean it can't or won't happen in the future. But when asking "why hasn't it succeeded?" I think it's one thing to keep in mind. It was certainly something which the Bolsheviks, for example, kept in mind. They knew they were departing from "the expected norm," but they fully expected the rest of Europe to join them very shortly in overthrowing capitalism, which was what would make their revolution worthwhile. As we know, that didn't happen, and the rest of the Soviet existence can effectively be summarized as "dealing with all the ramifications of that fact."
3. How many hours per week will we need to work and when's the pension?
Not up to us. One of the key aspects of Marxist socialism is that the new society will decide its own shape. We are not the utopians of old, deciding beforehand from on high how the new non-capitalist society will be. Our expectations are derived from theory: we have observed the patterns of human behavior in the past, and the dynamics which have shaped old and new societies, and used that to extrapolate just how this one will end and what the new one might look like. Minute things like "pensions" are not included in that.
4. How will people end up with the more taxing jobs if there's no incentive to work there?
Compulsion is not the only thing which makes people function or do things which are not "pleasant." People do lots of things simply because they need to be done.
5. Will there be luxury items? Is there a way to save up for a Porsche if I work hard and only eat oatmeal at lunch?
If you like. But in communism there would be no such thing as money. Objects would be produced by necessity and for consumption, not for exchange in markets. Until then, however...
6. If we had a long lived communist state - would we attempt to spread it to our neighbours in any way?
I think communism can probably only exist once capitalism ceases to.
It's what we are here for.