Whosoever was involved in writing that communist manifesto seems to me like the biggest idiots ever, in existence.

(2)&(3): In a free and deregulated market, workers who feel like they’re being underpaid will always, either find a higher paying job (because there’s much more competition which cannot be eliminated, unless companies bow down to the demands (which are achievable) of each and every consumer, which may even be impossible, in case of conflicting demands), or create new competition with ease.
What they’re considering is a practically impossible edge case, if libertarianism is in effect.
Secondly, eagalitarian society holds no importance at all, because, if there’s a class of sufficient size, that has a low income, there will always be a market for serving them. To put it in other words, in a free market, you simply cannot hire workers without paying them enough for survival, because there’s so much competition out there.
(4)&(5): Totally false. They always exist. The swings are more violent in an interventionist government. The more you intervene, the harder recession hits you, because intervention competes with fundamentals to drive investment. The government is the worst at knowing what people need, because of its centralised nature.