Thank you for engaging in good faith. People downvoting you are unhelpful shit-slingers. They probably haven't engaged with theory much (or at all), since the questions that you're bringing up are some of the fundamental conundrums that a viable socialism would have to grapple with.

I won't dive too deeply into your specific questions, but I'll offer a somewhat utopian framing that might help. A lot of these questions of ownership, labor, buy-in, profit, and so on arise from the difficulty in seeing beyond the current structure of our economy. Not only is the current regime of private property and labor relations a relatively new invention (~1-5 centuries, depending on how you slice it), but the system is, for better or worse, constantly evolving. Unfortunately, people are taught that we have reached "the end of history", where no more fundamental societal change need be made.

When private property is able to be permanently abolished, it will be because the concept no longer has any meaning or benefit to the citizens. What good is private property in a world where the gains of our collective efforts are shared to meet everyone's needs? How does such a society reward people who engage in an exceptional amount of effort or risk, without those rewards coming at the expense of others?

Almost all "left" political tendencies agree on the goal: a society without exploitative hierarchy, an economy where prosperity does not necessitate hardship among a subset of the populace. That's the utopia we work towards. Your questions and concerns are the "nitty-gritty", the issues that must be resolved for us to reach utopia.

The current system has enabled tremendous prosperity, but that prosperity is built on the suffering of others. Capital accumulation and the development of the "free market" has enabled tremendous technological achievements that could ultimately serve the prosperity of all humans, but those achievements are distributed unequally by design. "There is no ethical consumption under capitalism" isn't a moral condemnation of consumers or small business owners like yourself, but an acknowledgement that the system itself runs on a certain level of suffering or inequality.

All this to say that your concerns are valid and that struggling to see an alternative doesn't make you a villain. A better world is possible, but it won't be easy to get there.