Hi there,
To use clay, simply mix it with an equal amount of distilled water, or stick-blend it into your oils before you add the lye solution. A little bit of clay goes a long way; too much can make the soap brittle.
To use an infused oil, measure it out like you would any other oil in your recipe.
For instance, let's say you have created some paprika-infused olive oil.
If your recipe calls for 100g of olive oil, and you want a deeper color, perhaps you would use 100g of your infused OO.
If you want a lighter color, you might use 50g of the infused OO, and 50g of regular (non-infused) OO.