But if the universe is expanding faster than the speed of light, any signals may be moving towards us as fast as the emitting object is moving away from us. Thus those signals could be relatively stationary, or even becoming further away.
I thought that the speed of light was a constant (in a vacuum), and therefore independent of the speed of the emitting source.
Strictly speaking, yes. Perhaps I didn't phrase it quite as accurately as I should. Perhaps it would have been better to say we could be travelling away faster than the electromagnetic wave is travelling towards us. And an object cannot travel faster than the speed of light, but the universe is not an object in that sense, so it doesn't have to obey those laws, or so they tell me.
The observable universe, or if you like our furthest limit of vision in the universe, is becoming less, not more, due to the expansion of the universe.
Also, it's taken us 13 billion years to evolve into what we are today, since the big bang. Any other potential life force out there has had no longer to evolve than that 13 billion years.
Add into that mix the potential bending of electromagnetic waves, and other anomalies, as suggested by fender, and the potential for detection or communication reduces.
So theoretically, there may be "klingons on the starboard bow" but we may never be able to communicate, detect their presence, or they ours.