Is money taken from self-employed workers under your sponsorship permissible, especially when you spend this money on your personal needs? And is money resulting from employing workers under your payroll, and then having them work for someone else for a higher wage, permissible?

Having workers under your sponsorship does not permit you to take a percentage of their salaries except by a legitimate right. However, it is permissible for you to agree with them on a specific salary, and then lease them to others for a higher wage and profit from the difference, because by doing so you own their usufruct and utilize it within the terms of the contract.