The same way you use ordinary sugar - add it to the yeast. Castor sugar is just ordinary sugar but finer/smaller crystals.
I have tried it and dosent make much of a diffrence!
caster sugar
There are many places one might go to learn more about caster sugar. The Cake Central website is one such resource that one might go to reference caster sugar.
Generally, the sugar used is caster sugar, but any pale fine sugar ought to do.
yes, they are the same thing
The higher the proportion of sugar in a cake, the lighter it will be (up to a point). However, the downside is that as the proportion of sugar increases, so does the stickiness of the crumb, and as the crumb gets stickier, the cake will be inclined to rise less. Using caster sugar instead of granulated sugar will result in a comparatively fluffier cake.
yes, I have done that several times and it is very nice!
Caster sugar is heavier.
In America, caster sugar is called superfine sugar.
Self-raising flour, caster sugar, hard margarine, eggs and cocoa powder
2 to 4 eggs caster sugar self rasing flour
Caster sugar is called "superfine" sugar in the United States. Do not confuse with confectioner's (powdered) sugar to which cornstarch has been added.