Shanghai railway station to pudong airport

I will be traveling from Nanjing to Shanghai by rail on Tuesday. Can I leave my luggage at the railway station while I do a little bit of city seeing? I will then need to get from the railway station to pudong airport for a flight to HK. What is the best way to get from the station to Pudong airport? How long does it take, and how much does it cost/ Taxi / Tube / Bus?

Thanks for any help and clarification.