Crudités is a French term that refers to raw vegetables, so a platter of crudités typically consists of one or more types of vegetables served with one or more dips.
A double boiler is used to heat something delicate, like milk or chocolate, that is at risk of burning if you put it over a direct flame. You can buy a real double boiler, but in my opinion there's no point because you can so easily make a fake one using other kitchen tools you already own.
Store-bought margarine is full of chemicals and other weird ingredients. Try making your own vegan butter instead - it acts just like the real thing, and tastes similar.