It is not rush at that time and it will be much easier to get train booking and move around, for the May Day holidays only last three day from May1 to 3. You can book the train ticket once you arrive in the station. The best way from Pudong to Shanghai should be the airport bus line. Line 5 runs from Pudong Airport to Shanghai Railway Station. Line 7 runs to Shanghai South Railway Station. As to the hotel, Super8, Rujia are fine.