Ok, this is getting huge, so I'm going to try and pick a few point and focus on them, so please don't think I'm just ignoring other parts of your argument, we can return to those later assuming this keeps progressing.
That in mind I'll start here:
"This is an unreasonable assumption unless said combined powers can get away with using force or fraud to monopolize their market. First, they cannot, by definition produce the same product with lower-skilled employees."
At the risk of sounding socialist I think this real world example is very important. After California privatized their electrical market Enron scooped up the right to produce. They then IIRC divided the grid into smaller subsidiary companies and through the central ownership of these smaller subsidiary companies created false shortages and rolling brownouts in order to justify higher prices for electricity. As there is no competition for electric power providers in a given area residents had to pay these higher prices or live without electricity. This killed people as some elderly unable to cool their homes due to the rapidly increasing prices literally smothered to death.
I agree about the monopolizing through subversive legal means but rules without the means to enforce them leaves a bevy of other problems that could manifest, another example being the "Blackwater" agency. Basically a privatized army acting on behest of whoever pays them the most. If Minisoft can't subvert legally because there is no institution to do so with, they can manufacture their own "enforcement" to maintain their control of the market. This is basically the premise of Cyberpunk and Shadowrun RPG's. The government is completely ineffective and large companies have private police and armies to maintain their interests.
This is incredibly important considering current GMO trends, as companies have attempted to patent life. Assuming they had succeeded in any real fashion, a company that creates a gene-modification that corrects downs syndrome in the womb, the resulting child would be just as much property of the parents as property of the company. This could result in the child having to pay a special breeding cost in order to produce a child that may or may not have said company gene as that would be a copywrite violation of the companies gene-code. Doctors may not be allowed to operate as it may alter gene-code and disturb their product. Imagine being denied insurance because the company doesn't want someone to "Jailbreak" their "property".
Why is Round-up so popular? It has a farm subsidy monopoly. Roundup has no fear of ever going out of business as it is the sole pesticide available for use if a farmer plans to use farm subsidies. Monsanto seeds are also the sole seeds provided for by farm subsidies, and both Monsanto AND round-up are owned by the same central company. They have the illusion of competition, but there is absolutely no way another pesticide or seed program will ever be able to compete with them as their control of the market is completely dominating and they now have the capital to always outbid any other company for that right to be the sole beneficiary of government farming subsidies.
That being said, companies can get away with this kind of manipulation of the government in part because of political leaders ignorance of the means of manufacture and the acceptance of corporate sponsors of politicians. Current politics in America are forced to complete on a corporate field and corporations are beating them with experience. Regardless of a politicians intentions, they will get all of no where if they attempt to disrupt the flow of easy money as their voice will practically never be heard.
And this brings us to reputation.
Reputation isn't something you give yourself. You cannot create your reputation. Reputation is a manifestation of the popular opinion of you. You could be the most honest, hard working, dedicated humanitarian in the world, but if the popular manufactured consensus is that your a homicidal maniac rapist, that is your reputation. Wether a rumor be true or not, it can destroy a human life as well as a company. There is absolutely no legal or social defense against a rumor, and the further the rumor spreads from the individual or company, the more likely it is to be believed and by more people, which creates a kind of domino effect back to the target of the rumor creating doubt and misgivings in even their closest of acquaintances.
The only thing even remotely capable of derailing misinformation(rumors) is an unbiased media. If the media is used to create a paradigm and reinforces that paradigm without offering complimentary debate and discussion of "the other side of the coin" than people as a whole will simply not have the tools they need to make informed decisions about what is going on, and can be easily persuaded to accept said paradigm as truth.
The major concern I have with talks of dissolving the governments power to regulate and enforce regulation is simply put, Mob rule.
It is unfortunate that many of those who have been elected to act on behalf of the people are in fact acting on behalf of large corporate interests. To me, it feels like current politics has become not a means to enforce the will of the people, but a means to add good resume' points to the highest bidder and politicians have no fear of repercussions as each election cycle brings the false hope that this will change and the blame for said problems shift from them to the newly elected representative, and as the media in america no longer presents unbiased information and actively promotes the violent silence of any voice of opposition and creation of sensationalism the power of the people to make informed decisions become even more precarious.
The current trend of "censoring the internet" is reminiscent of the "turkish coffee house phenomena", where once coffee was introduced to a region, coffee houses started popping up. As previously after a hard days work, people would go home and to bed, people started going to coffee houses and socializing as coffee gave them a little extra energy to socialize. Through this socialization, by talking to each other and discovering each others problems they realized that their oppression and hard times was a direct result of an overbearing government. The Government then tried to ban coffee houses to prevent open discussion. This is what the constitution is referring to by "Right to gather peacefully". It is not solely for the right to protest, but to gather and have conversation and debate about what is bothering you about the current state of affairs, and what you say about the current state of affairs is protected by another amendment called "Free speech".
Back to Anarcho-capitalism. I feel like it fails to take into account that we are not the only country, and sans a central leadership to mobilize a cohesive physical defense other perhaps "less enlightened" interests could easily view our vast resources as easy pickings. It is unfortunate that the current government has allowed giant corporations to exploit our vast resources and then proceed to other countries to exploit their inexpensive labor, getting the best of both words at the expense of the american people, and the reputation of america globally. The central leadership provides for an army to prevent the physical assault, but fails to provide the wisdom from a more subversive intellectual assault and at this time I feel that is their greatest failing, however a failing that could easily be remedied should an unbiased media be allowed to explore in depth the problems we a currently experiencing.
I started here because these felt like the most important talking points to me as they seem like the root of the other issues we were discussing.