I wish I had advice. I wanted guineas so bad but the eggs I incubated didnt hatch. Out of the 13 eggs I bought online only 4 were actually fertile and of those they were shaken to bady by the postal service. Maybe next year I'll try again.
I don't know where you're located, but they probably won't need any extra heat in the type weather we've been having. The main thing is to make sure they stay dry. They can get wet in the morning dew and up to about a month of age, can catch a chill very easy.