The yeast is treated the same whether you use a stand mixer or a food processor. If you are using active dry yeast (ADY), it should be proofed in a part of the water called for in the recipe you are using. That water should be at around 105-115 degrees F. If you are using instant dry yeast (IDY), it does not require proofing in water and can be added directly to the flour.
If you are using a food processor, I suggest that you add the dry ingredients first and then the liquid. Otherwise, you can gum up the machine. For a stand mixer (like a KitchenAid), I do the reverse, that is, add the liquid first (or at least the bulk of it) and then add the dry ingredients.