hi

Just a question, but if you are making bread homemade, why would you want to put additives in it? Homemade bread lasts almost as long (depending on the temp of your kitchen) as the store bought stuff. It also freezes well.
If you are talking about additional ingredients, you can put almost anything into bread. Fruits, nuts, vegetables, different types of grains and flours. The only thing to be cautious about is adjusting the amount of liquid needed for additional flours or fruits/vegies. If you are using a "wet" ingredient, you may need to decrease the amount of milk or water you add. If you are adding a "dry" ingredient then you may need to add more water/milk.
Hope this helps! :) Happy Baking