When you place bids/offers, it works on the underlying price. When you put in your Stop Loss, you use the SSF prices. There is a matrix where you can see what is the SSF bids/offers on the different underlying share prices. Std bank is rather stupid/annoying/non-user-friendly in this regard, but thats ONLY MY OPINION.
A word of advise using SSF stop orders. They really are for last resort only, and they don't do a very good job of negotiating the best price. They will take the first bid that comes along, so if there is a big bid/ask spread, you are going to lose a lot. (Losing a lot is better than losing it all though). IMHO, if you are using futures, your view is short term by definition. Best keep a sharp eye on the price and exit before your stop losses kick in.
It's true, but you can also put a limit on your Stop Loss to make sure that you don't get out at a ridiculous price. Make sure you have a SMS warning at the price of your Stop Loss, and get to a PC as quick as you can to see whats happening, just in case the share starts running/dropping bigtime. You can also phone the support to get the latest prices or to trade via the phone.