You won't keep the momentum. Think of it as a burst of leads, similar to having a booth at a trade show.
do you (or anyone) know how the tail off it. Is it pretty much dead after coming off the front page for example?
Typically yes, but prior products can make their way into lists, where they'll traffic down the road. As for when traffic will die down, honestly, I'd say within a day or 2, based on how people use PH.