I find this thread strange it that the title starts with the idea of proof of life or no life, and then immediately we are into discussing Star Trek like scenarios. There are two considerations. First, we currently believe that the light barrier is not breakable, and hence traveling is going to be slow and time consuming. Second, how did we go from "life/no life" to "intelligent life with advanced technology" so fast?
In the near future we will be able to analyze the atmospheres of many of the earth-like planets that have been and are constantly being discovered. We might find good evidence of the signs of life on one of those planets. This might indicate that life is likely there but we won't know how complex that life might be, or whether intelligent life is there, or whether technology exists there.
This could be the basis for sending a probe. But, it might take centuries to get one out there and get answers back.
But just knowing that any kind of life is out there will be an earth-shattering discovery and possibly the greatest discovery in history.
Now imagine that there is a primitive intelligent life out there, and we send a probe to their planet. and they see our shiny reflective satellite go into orbit and take up the task of monitoring the planet. We may be the alien invaders depicted in so much of our sci-fi.