Speaking of deterrents, it can help a lot to simply have a sticker on your house or sign in your yard of a security company, even if you don't actually have a security system.

I'd hazard a guess that while it may be as annoying to you, and receive the same inaction from you, that to each owner a dog's bark has a different meaning. Partly because they get to know the animal ("oh, he never does X or he usually does Y so I can judge this better") and partly because they have context (all you hear is barking, but they hear that along with... knowing the dog hasn't had his walk yet. Or knowing he was asleep so something strange must have woken him up. Or knowing... etc.)

Depends on the kind. For the most part, if one keeps barking in the night, you can assume something's wrong. If it does it anyway, you already know that and can ignore it, and call the council if it keeps doing it.