Nope, PI in the end zone gets put at the one, even if it's already there. E2: Apparently it is half the distance? I've heard a number of people on radio/TV talking about it like it would just go to the one again, and that's how I've always thought it was enforced, but maybe not? Looked it up and you are correct, if the line of scrimmage is inside the 2 it's a half the distance to the goal foul.
EDIT: And apparently the Giants had a couple players injured the last time they tried the tush push, so they may have swore it off. I don't think every QB/line can run it as well as Philly does - although we're definitely one of the teams that should be able to.