Either by personal drawings on the profits from your business, or by fixing a salary to pay yourself from your company (if that is the route you choose).
Yes you do. If you run a company, you will pay tax and national insurance on your salary. If you are self-employed, the money you draw comes from the profits of the business, and you will pay tax on that profit.
Dividends are a way of paying the company profits to you, the shareholder, if you operate via a limited company.
Only if the company is making surplus profits, over and above the salary it is paying you. We shall, though, always evaluate the most tax efficient way for you to draw funds from your business.