I really like this comment, you are outlining exactly the sort of things that our society has convinced us are ground state truths, that are actually just capitalist norms enforced by the State.
I really think you'd enjoy Peter Gelderloos' "Anarchy Works," because you can keep asking "but what about..." and the book will keep giving you examples from history to answer that exact "what about?"
To your points:
First, people don't do hard work for the collective benefit, they do it for the benefit of the owners of capital, who allow just enough leftover profit for people to keep themselves alive and for very little else.
A lot of that hard work isn't for the good of society, it's bullshit work that maintains artificial scarcity and the systems of capital, like the entire beast of health insurance in the USA, military procurement, landlord administration, advertising, corporate compliance rituals, or predatory lending.
Second, capitalism doesn't turn selfishness into selflessness, it rewards and selects FOR selfishness, and punishes and selects AGAINST selflessness. Why publish FOSS under MIT, the most selfless choice, when a major tech company will then just take the library, make money off it, and give you nothing in return? Why contribute to FOSS deployed by a big tech company when that contributes directly to a big tech company's bottom line for nothing in return to you?
Capitalism doesn't create incentives through rewards, it redirects people's inherent incentives towards less socially useful or rewarding projects that instead serve the needs of capital and the state. I read a lot about motivation to understand it in myself better, and one thing that keeps coming up as core to motivation and happiness is finding it inherent to a given activity, achieved through improving at and mastering that activity, and then being recognized for that improvement and mastery. Then, potentially, introducing novelty by finding something else to improve at and maybe master. Basically, humans love work, especially when it's useful or they can become good at it. Capitalism creates structures around this to try to redirect that labor to things that are useful first and foremost to capital.
Third, yes, a free market paradoxically requires regulation to maintain or it tends towards wealth accumulation, monopoly, and then as exploitative a labor relationship it can get away with - slavery, if it can manage. The free market is thus impossible because under capitalism, capital is power, and capitalism is a system designed for the accumulation of capital. More capital means you can chip away at the rules, which means more capital, which means less rules for you, and so on, until you get situations like today, where billionaires can diddle our kids and there's quite literally nothing we can do about it: the State's monopoly on violence is serving them, protecting them from us.
Fourth, people aren't considerate to each other because of the state monopoly on violence, they are considerate in spite of it, and despite the incredible violence the State and forces of Capital subject them to. Daily interactions are anarchist: you don't shove people out of the way on the street because it's illegal (depending on how you do it, it might not even be illegal), you don't do it because it's rude, it's antisocial, it will make people hate you, and because do it enough and you might yourself get slugged. Multiply this to basically every interaction, and then consider that the State isn't preventing the Big Crimes anyway like rape or murder, and itself facilitates the most widespread form of theft: wage theft and theft of profit. It doesn't stop or punish pollution, billionaire child rape, eviction, exploitative loans, or corporate fraud.
The State's monopoly on violence doesn't prevent domination, it enforces authorized dominion.
Will people work when there's no cash to gain? Well as you said, if their basic needs are met, why wouldn't they? If they don't have to dedicate at minimum 40 hours of their week to generating profit for some billionaire, what else might they spend their time on, and for what reason? Would they even need to work 40 hours a week if they aren't upholding systems of capital? Is their exhaustion inherent to the human social experience or an artifact of the artificially scarce society we've created? They already don't shove people out of the way on the street, there's probably some kind of social instinct there, right? What about you, in what ways would you contribute to the world around you if the world around you was already ensuring your basic needs are met? Would you look for ways to ensure the sustainability of those basic needs? Seek to improve comfort and delights? Seek to defend against exploitative forces?
Some other books you might like:
"Anarchy in Action" https://theanarchistlibrary.org/library/colin-ward-anarchy-i...
"To Change Everything" https://crimethinc.com/tce