as far as micing amps it all depends on the size of the room. Every amp has a certian volume setting that establishes that sweet sound that we all love, setting the amp too loud or too soft will often sacrifice the tone. What i always do is set my amp up and have a 3rd party wander around the room to see if it needs to be bleeded through the pa. One thing to remember is that if you don't go through the Pa your not going to be in the monitor.