1. I just don't think this analogy really holds up. The implication is that everything is local and dangerous when there is not even the slightest indication of such a thing as far as space is concerned. Traveling between star systems isn't going to be as casual as walking down the block. And even if it were, you'd think that any aliens then wouldn't be waiting on the chance of some radio signals. If they have the capability of traveling such great distances in reasonable amounts of time, then chances are they already know we're here. A flimsy radio signal isn't going to make much difference.
2. Yeah, I didn't mean regular radio broadcasts, but signals sent out by SETI and others deliberately.
3. Those odds aren't established. There's no way to know exactly what they are or if they even exist. My thought would be that it doesn't make sense for a civilization to use so much energy just to exterminate us, especially when we're really just contained here.
4. No amount of preparation is going to change anything. If there is a species out there that is a billion years more advanced than us, yet still hostile, then it doesn't matter if we wait a million years because they'll still be immensely more powerful and capable of annihilating us at any time. There is no catching up or sneaking under their radar. Either advanced species are hostile and we're fucked, or we're not. Radio signals aren't going to make a bit of difference.