Gapping is not just for spread bet companies, the market gaps in any stock sometimes.
eg Friday closed at 110, Monday opens at 120 instead of at 110.
No! LOL
You put in an order to go short at 100. The market is currently at 110 and closed at 110. The next day it gaps down and opens at 90 having completely missed your entry point of 100. Does the order get filled?
Not in that instant. It will get filled if the gap gets filled. Most gaps do get filled. It will keep going up, filling orders and closing out the stop losses behind those opening orders
so that those traders take a loss, then it is quite likely to start going down again, leaving a load of PO'd traders in its wake.