best way and costs from Shanghai to Great Wall and time needed for return. Also what to see in Shanghai.

It is suggested to fly to Beijing. Then use the airport express line to Dongzhimen Station where to change to subway line 2 to Jishuitan Station. Then you can walk to the Deshengmen Bus Station to take the bus line 919 to reach Badaling directly and vise versa.
The flight takes about two hours to Beijing and then to the Wall, it takes about 2 hours to the Wall. The flight ticket's price is hard to tell, because you may get a a large discount if you book in advance, so it is suggested to consult on the airlines' official website. The bus ticket is around 12RMB per person.

The attractions in Shanghai include the Bund, the Huangpu River Cruise, the Yuyuan Garden, the Nanjing Road, the Jade Buddha Temple and the Oriental Pearl Tower.