Regarding #3, why are these two things coupled in terms of page load? With all the js stuff you guys are doing now with instant, it seems like you could load up the ads on the right a split second after the search results and no one would notice or care...but I'm guessing you've tried this and it didn't test as well :)
Great question. The "don't wait for ads" policy has been around since ~2001, way before AJAX became common. In theory you could make it so that the ads loaded when they were ready, but that could also generate a visual "pop" that I imagine would annoy many users.
My preference is just to enforce a hard time deadline. If the ads team starts to miss that deadline and revenue decreases, then they're highly motivated to speed their system up. :)
