re: #1 Great White Snark
I’m pretty convinced this “paradox” is no such thing, and that it is hubris to think that we’ve been around long enough to observe enough to notice anything.
And as you point out, the overlap in existing civilizations are such that one has to be at just the right place and time to catch any photons they might throw at us.
Furthermore, given the inverse square law, even our most powerful broadcasts fade into the background noise after a few light years. If another civilization ever used radio then their transmissions too will be lost into the background noise after a few light years.
If we ever do detect intelligent life, I suspect it will be by observing their planet’s atmosphere as the planet eclipses the star, and we detect non-natural chemicals in the atmosphere.