I don't have time today to respond to everything you've said, so I'll just address your points on the USPS and Amtrak:
First of all, I do not favor giving USPS and Amtrak a monopoly over the mail and passenger train industries, respectively. Both industries should be open to private industry. I have no issue with the government having a postal service or public transportation service, but they should allow other entities to compete with them. The same goes for other industries, like the space industry (NASA has a virtual monopoly on launching satellites, although obviously launching rockets should be extensively regulated for safety concerns).
That said, there are major issues concerning instituting private mail and railway industries. With the mail industry, there are numerous complications when it comes to mailing overseas, where something would have to be worked out with the Universal Postal Union (which isn't going away). And with the railway industry, there is the massive issue of either coordinating private train companies using public tracks (and public stations) or creating an entirely new set of rails for private use, which is a huge can of worms because finding land to build these tracks on is very difficult. So with railways, at least, there are enormous practical barriers to creating a private rail industry today.
Oh, and a quick note related to trains and the stimulus because it is a monumental example of doing things the wrong way. Obama set aside a large part of the remainder of the stimulus aside for a high speed rail system. Upgrading our railways to a high speed system is a great idea in theory, because high speed railways are more convenient for the public and are more efficient. This typically leads to higher rates of train use, which allows for cheaper intercity transportation and has the happy effect of reducing gasoline consumption nationwide. However, implementing such a system will require a lot of capital and is thus best-suited for private investment in a system in which the government runs the rails and private companies run the actual trains (basically the same setup that exists with airlines). Instead, Obama allotted some eight billion of dollars to be distributed among proposed individual high-speed rail corridors that do not have the necessary funding to actually be built, thus wasting the money when we could have applied it to something like the more recent small business aid package.
The problem with Democratic initiatives this cycle is that after finally getting control of the legislature and presidency for the first time since the 103rd Congress, they're trying to implement everything that's been on their agenda for the past decade. The problem is that they also came to power with a big deficit and terrible economy, so these programs take a big problem and make it even worse. I mean, if the government decided to invest in high speed rails when we had a surplus, it would be one thing (not necessarily a good thing, but not the end of the world), but by throwing $8 billion at high speed rails when we already have a huge deficit is just nuts. If we're going to invest money in all of this stuff, can we at least get something out of it?!
Suddenly, this response doesn't seem so quick. And I'm late...