could you use fresh yeast instead? if so whats sort of quantity?

Hi Miles! According to Cook's Illustrated, here's the conversion you would use: "To substitute fresh yeast for active dry yeast, use a ratio of roughly 2:1, i.e. use one small cake (0.6 ounce) of compressed fresh yeast in lieu of 1 packet (.25 ounces) of active dry yeast."