Thanks, that was a very thorough response. Deriving benefit from a shabbos goy is very limited but there are ways to do it. For example if a gentile housekeeper turns on a light in a room to find an object that her Jewish employer had requested, the Jew may then derive benefit from this light. So, the Jew knows to ask that the gentile do something that will inevitably result in a light being turned on. However, a Jew that asks a gentile to turn on an oven during shabbos is prohibited from deriving any benefit from that oven and any food subsequently heated would be permissible to eat until it has cooled again.