If you've got 8 hours, you'd be better leaving the airport for a few hours. There are loads of bars and restaurants very close to the airport. Ask for the Le Meridian Village for a good place to start.
You should get both your boarding passes at the first airport. You can then freely leave the airport and return with your second boarding pass.
Give yourself 90 minutes or so to get back into the airport.
Y - Economy
J - Business
F - First