The advantages and disadvantages are not far from the ideas you already know, that it stops you from making too much loss. But personally, I would say it gives you the opportunity to retain your account so that you can try to regain what you have lost next time.
Stop loss are usually placed with a buy / sell order.
This is confusing. Stoploss order is not only made immediately you place a buy or sell. It can also be adjusted later when you have already placed the buy or sell order.