Ok thanks so much for answering my first question and partially answering my second. What is an "alt" chord? What other extensions are there for blues chords?

I also noticed that i dont need to striclty use the minor pentatonics when playing basic blues (its harder to fit patterns on piano). I usually grab notes from the major scale. E.g whenever i play E7, i can safley play the G# and it'll sound good. So does this mean that blues isnt striclty stuck to the minor blues scale?