Yep! The definition of parallax is that it's when a position or movement of something differs based on position of observer.

Yes, parallax is the change in the apparent location of an object in the sky to an observer as the observer changes their relative location to it, e.g. by orbiting the sun. And, if you mean software, a lot of astronomers use old stuff like Fortran and IDL but modern tools like python and julia are becoming very popular.