Yes, many scientific theories (as opposed to science itself, which is a process) keep changing. That's how they get closer and closer to the truth.
It is extremely rare for a widely held theory to be completely disproven and replaced with something quite different. It's far more common for an existing theory to be supplanted with a broader one for which the previous one remains a very good approximation to the previous evidence. Einstein's modifications to Newtonian mechanics are the classic example.
Exactly, Newton's Laws are still valid, Tsiolkovsky rocket equation, the physics equations of movement, velocity and acceleration haven't been overturned.
