Stop-loss orders without a limit price are seen by many as very dangerous (more like a loss order ;) ). If the stop loss feature doesnt allow you to set a limit price, don't use it, it will do more harm than good.
Margin trading is a whole another beast. Pretty much guaranteed your position will be forcefully sold for practically nothing if a flash crash happens. Worse, if you are in multiple margin positions then your other positions may also be sold to make up for losses from the first position, effectively emptying your whole account.
This is exactly why there are so many disclaimers and terms you have to accept before margin trading. Just don't do it.