2nd topic: how does a clay teapot impact tea?
Clay is made up of minerals, it can neutralize chemicals dissolved in water and tea. Wonder why natural spring water taste great and crystal clear? Evaporated water is pure water, however on the way up to the sky and coming back down to earth as rain or snow, dirty dust and chemical vapor polluting our air attache itself to tiny water drops. Rain become solvent of these unwanted substance drips back down to earth, runs through miles of rocks in river beds and streams, naturally filtered by these rich mineral deposited stones and rocks.
A clay pot is similar to a rocky river bed, pores allow tiny air hole to increase oxidation, porous clay teapot can oxidize and neutralize dissolved chemicals/minerals in water/tea, hence improve taste of liquid in pot. However by doing so, it may also diminish flavor of tea depending on dissolved substance of a particular type of tea leaves. That's the reason why some tea taste better with certain clay type and some don't. The same tea pot may not be good for every tea.
Everything revolving tea is not absolute due to element variations, so much like life, therefore our endeavor of preparing a cup of good tea is never ending. It's a perpetual pursue of experiments.