One way is as the name suggests, and it is a real theatre the last time I was there in the late summer. Essentially you can't walk around freely but only as if you are on one-way roads. Booking with ANA doesn't give you the right to enter the ANA lounge, but it is a *A lounge, so I suppose you could access it. I'm not sure if it's in the Schengen area, so you may have an additional transit, but as CWS suggests, it is unlikely the shower facilities will be open by the time you travel.