(2) & (3) De-regulated labour markets are not in perfect competition. There are always more people selling labour than those who are buying labour. That results in a market where wages are lower than their optimal level with additional economic rents extracted by the employer with lower overall productivity and with the cost borne by the worker and everyone else (due to losses in productivity). This is pretty basic stuff that you'll learn in second year economics.

(4)&(5) The empirical evidence doesn't support your claim.