Physical proximity matters. A remote person who seeks out and looks at the photos is probably at least an inconsiderate jerk. A person who trespasses onto your property and peeps into your windows is not merely an inconsiderate jerk, but represents a potential threat to one's physical safety.
Definitely not. Doing so is to much of a slippery slope when extended to drugs/alcohol or anything else that has the effect of lowering inhibitions or increasing the likeliness of committing a crime where one might otherwise not.
That said I agree with your point there is a blurring of the line. Whereas in your example, one would have to actively go to someones private property and peep through a window until they caught what they were looking for, versus the internet where a picture practically comes to you, your only act is clicking (tptacek touched on this...maybe could be termed "lowering the barrier to criminal behavior"). So while the victim impact is the same as you say (I might even argue online is worse because there is greater/continued victimization), the acts are different in nature. Blurring the line further is that culturally the internet pictures are normalized in the sense that they are practically marketed via traditional news, social media and late night comedians as things to see rather than condemned as acts of victimization.
[1] And that's the value of analogies--not just to help us understand things that are novel in terms of the familiar, but to help us think about how things are similar or different, which helps us cut to the heart of why we think about a thing in a particular way.
Pictures do not passively "leak" online. Someone goes to the trouble of posting them. If that person didn't have permission to do so, they are the guilty party, not some random person who happens to see the picture, not even knowing who that picture is of.
This is the same as if the peeping tom snapped photos, and then shared them. You're not automatically a wrongdoer just because you see such a thing.
Pictures leaked before we had the Internet. Hello? We had scandals revolving around leaked photographs of famous people decades prior. Paparazzi also existed long before the Internet.