@always_ask_questions
I don’t understand most of what you are asking. all these things are dealt with as basics of shulchan aruch. Do we not have a Torah that tells us how to know what to do?
(real) poskim have always labored to explain their reasons so that we will know how to apply the rules to the next situation. one simply cannot paskin if he doesn’t know the sources for what his rebbe taught him from. if you can’t paskin, you depend on what you already have or turn to someone who can paskin. again, all this according the basic klalim of psak well explain in shulchan aruch.
