There's a reason that most people who believe in libertarianism are in high school and have zero experience with the real world, and you and Atlas illustrate it quite well.
You're making unfounded assumptions. Foolish ones, at that.
But let's address the easiest to knock down, first, shall we?
Companies (not 'Corporations', those are the bastard children of Government)
You know, just because corporations started out with government charters 400 years ago doesn't mean you can blame government for their existence and every single one of their crimes forever. I don't know how you expect to have companies that operate on the scale of modern corporations without some kind of corporate model. There aren't many single people who can afford to set up, say, a $4 billion semiconductor fab plant. Moreover, privately held companies have committed so many of the same abuses that corporations have, so I don't see a hell of a lot of difference from a human rights perspective. Hell, the people who are spreading some of the most ridiculous and misleading propaganda out there are the owners of a private company:
http://en.wikipedia.org/wiki/Koch_brothersAn untraded corporation is still a corporation. Offering stock can be done without incorporation, and incorporation can be done without offering stock. It's the limited liability that is the issue here, not the stock offer.
This article may assist your understanding.
Charities pick up the slack on things that can not be provided for profit, such as homeless shelters, and the like. What government calls 'social programs' This would also include pure research projects, such as deep-space probes.
Even with the government providing social services, charities are always desperately underfunded. How overwhelmed do you think they'd be without a social safety net to pick up some of the slack. Especially with people making less than minimum wage, which means you'd see fewer donations and far more need.
Here, you're ignoring the source of the funds that pay for those social services. In another thread, it was discussed in some detail how those who actually cared could completely pay for almost all the services with very little trouble. You care so much, however, that you want to make sure that everyone helps, even those you're 'helping'.
The Media keeps these two honest by investigating and reporting on them. If you're worried about bias, seek the opposite bias (you can count on Pepsi News to report on Coke's misdeeds, for example),
And when Pepsi and Coke advertise in all of the same media? I also don't think I'd trust one company to be truthful in telling me about the misdeeds of their competitors.
This is actually the one valid point you make. and it is for that reason that I'm a fan of No Agenda and other community supported projects.