percentages

I am a newbie who loves to experiment.  From my reading and experimentation I have learned that successful breads roughly have a 3 to 1 ratio of flour to liquid.  And that dough can tolerate a certain amount of "additions" such as nuts, raisins, sundried tomatoes, etc.  Most recipes that call for additions have 1 to 2 Tbs. per cup of flour.  So, my question is. which of these things function as flour (have to be counted towards the hydration) and which ones are additions?