> Let's consider for a moment what it would mean for corporations to not have free speech.
Let's not! You don't get to change a contract because you don't like what it could mean. Take it up with your congressman and get a constitutional amemdment passed if you don't like it.
> First, it would mean that we would need some sort of government department to determine what speech is permitted and which isn't.
You mean like the courts??
> Then, we will need to determine which corporations are going to be regulated, and it what ways.
Easy. All of them. In any way the government sees fit. Because their incorporation is not a social club but a legal entity that engages in commerce. And commerce is clearly and plainly defined as regulated by the government. The legal construct of a corporation itself only exists because they are regulated without any rights. That's why you can shield yourself from many legal responsibilities by setting up a corporation (even anonymously in some states), because its not a human with human legal accountability. If not so then when a corporate decision kills people, everyone in the corporation should be thrown in jail. You can't have it treated as a person but only when it is convenient to line up your pockets. Which is what is happening now. Decisions made by people acting as officers of a corporation are not protected by any rights, period. That same person can make that same decision as an individual and it would be protected by applicable individual rights.
> And what about books? So I can self-publish a book, since that's just me. But if I decide to use a publisher, is the content of my book now regulated?
The government, by censoring the publisher is censoring speech made by a non-employee individual author. Also for this and many if your assertions, corporations who are presses have a special right. There wouldn't be a need to call out the press in the first amendment if presses were by default humans because then they had freedom of speech already defined for them. Corporations and companies have been around before the US constitution (ever heard of the easr india company?), to my knowledge, thhe press is the only time a corporation is mentioned in the constitution. This also implies that corporations who are not pressee can be censored from publishing things the government dislikes.
> Does this mean I cannot incorporate to make my taxes simpler and to separate my personal liabilities from my business liabilities?
Yes you can, but you can't escape liability as a business and then turn around and also demand rights as if you didn't separate yourself from it. You can't escape responsibility and then demand rights that come with it.
> Hopefully this helpa you understand why this isn't such a straightforward issue
It is a straightforward issue. A "person" in the bill of rights is human like organism that emerged from a woman's vagina.
What's next? You can't contractually force companies to do work because they are people and slavery is illegal?
The truth is, the wealthy ruling class have made it so that they can use bullshit like this to gain unequal treatment under law.