I don't understand the fundamentals, so i would not trade major news, including NFP. on major news days like NFP you should not be in the market at news time. you should wait 10, 15, 20 minutes after the news announcement, then jump in at some point and catch the trend if there is one.
NFP is way to volatile. people have a tendency to get whipsawed at NFP.
I agree, you can't really guarantee your stops or against slippage during news. There is simply no guarantee against losing an entire year's trading gains in a single minute.
I think trading near news is easier for those of us who understand fundamentals, which I personally don't.
The reason expectations ahead of the news release are just as important to price as the result of the releases is that the expectation itself is 'priced in' to the value of that currency, and once the news is out, so to speak, then the price the currency 'should' be at is approached rapidly.
Some of that approach can be in the days, hours, or minutes before the news as well informed traders make their trades. There is some effect of the price level resulting from the expectation, just as any uptick or downtick resulting from an event or a large trade can effect future prices based on what traders see on their screens.