Anarcho-capitalism is far from an oxymoron. Capitalism is a market system with no interference from the state. Anarchy is the lack of a state/government. So really, they go hand in hand.
I suppose it depends how you see capitalism. In my personal view the result's can be quite negative. As in the freedoms of a person would be hindered if surrounded by monopolies and low wages.
1) The currency would be whatever people are willing to accept in exchange for their goods and services. It wouldn't be a fiat currency, like we have now, because nobody would want useless, green paper.
Not all currencies are fiat currencies and I do see your point. The only problem is that trading without a common standard currency becomes incredibly difficult. Many inefficiencies would arise from the problems in calculating the "value" of items. For instance, how much value does a Roma football stip hold? Someone may offer 1 chicken from the US but a Roma fan may offer tons of chickens because he values it more. Another, more sensible example is if I want to buy a cow from you, how the hell do I know how many of my chickens to give you? It makes it a very difficult and inefficient system. Imagine trying to pay in stores or online.
I see your point. Why should a builder have to make a factory to get the bricks and only then start the building? The thing is, he doesn't. The point you have made is that natural hierarchies are made because of the corrupt and power hungry. This usually ends up with dictator's, criminals and bad men owning big monopolies. You can even see when you put a bunch of new people together very quickly you will be able to notice who has become the top of the pecking tree and who is at the bottom. The role of a government in a democracy (America = "two party democracy". Now THERE's a oximoron for you!) is to reduce the negative effects of these bad men on the rest of the people. I agree that no government is perfect (many far from it) and often you do end up with bad people in power however it is better than the alternative's of dictatorship or freedom's crushed by mass monopolies.2) I can't attest to whether or not a social hierarchy is human nature, but of course, not everyone wants to be a factory owner, for example. Most people will simply choose to "lease" space in the factory, and collect a smaller percentage of the full value of their production, in exchange for access to the means of production (tools, machinery, whatever) from the factory owner. This is a win-win trade. Workers get paid, and the factory owner collects a profit for putting his money on the line and assuming all risks. No body is exploited because it's immoral to use force against another to get what you want. Everything is purely consensual, and everyone gets what they want.
This is all simple stuff that I'm sure you understand.
However, things get tricky when the government steps in. No longer are people free to spend or save their money how they choose due to taxation. Instead, a large percentage of their money goes to causes that the majority, or more likely a select group political elite, believes should be supported. If you don't agree, you can expect to have your freedom and property stripped from you through force and violence.
You, of course, have to account for people with the desire to exploit others for their own benefit. These exploiters are drawn to positions of power, aka political positions, to further increase their ability to exploit.
OK OK, I'll finally get to the point.
I wouldn't say hierarchies (governments) are desired by humans as a whole, but rather, are desired by the corrupt so they can exploit the masses for their own benefit.
The desire for concentrated power, and the taking through violence that is spawned from it, is an incredibly primitive way to look at the world. I think many more people would agree if the corrupt weren't doing everything in their power to convince the masses that violence is the answer by veiling it under the guise of freedom and social justice.
Sorry for the wall of text.
3) In an anarcho-capitalist society, the only "rules of the game" are that nobody can infringe upon or take through force one's right to life, liberty, and property.
In today's society, the opposite is true because the rules apply to some, and not to others.
The only problem is how many people will actually stick to the "rules of the game"? Someone stated an argument earlier that I would be interested to hear your thoughts on. You say nobody can infringe upon or take through force one's right to life and liberty. Who is there to protect it? In most modern societies it's the police. I honestly can't think of a world with no police, imagine the huge levels of crime. Also you state "property". If there was no government intervention there would be no minimum wage. There is nowhere near enough value in the world to be shared around so I don't see how the vast majority of people would be able to afford housing. In this kind of system I can only see the rich getting richer and a growing working class.
In my person opinion the idea of having completely personal freedom is a lovely idea however it is just an ideal. It seems just as impossible and impractical as communism.
Again, I hope someone more intelligent than I can weigh in.
You have made the best discussion so far. I find some people make the argument rather ... personal and tend to not answer the questions. Thanks.