I believe there are other civilizations in the galaxy. I believe that a smaller number of these civilizations developed FTL flight and have colonized other systems. I believe that our civilization and theirs would be alike in many ways, but different in other ways.
I am dubious that an advanced civilization would send a crewed ship to explore a system. I think they would do what we are doing - first, explore a system using telescopes to see what planets are orbiting a system, then send a space probe to the most promising systems for an in-depth examination. I think colonization would come later, and I think expansion would come about like the Polynesians settled the Pacific Ocean.
I think it's possible that we have already been scanned by other civilizations. I think it's possible that our system has already been visited by one or more probes.
As for these civilizations being able to pick up and comprehend our radio transmissions, could they? The galaxy is filled with sound. Now, it's not sound like we know on Earth. This sound has to be picked up by specialized equipment that is designed to synthesize the sound into a form we can recognize. We can now hear the 'voice' of our star and its planets. I would think these sounds would drown out radio transmissions the farther out they are from our system. Furthermore, our space probes are designed specifically to respond to radio signals. Has anyone done an experiment where the space probe has to find a radio signal from all the other noise out there? I think it's foolish to think that an advanced civilization would dedicate its resources towards picking up a radio signal from another civilization. Even in our world, we are working on the next phase of communication based on quantum mechanics.