i would like to visit the great wall/Beijing in April,2016,will it be very cold then?

April is actually one of the best months to visit the country. The temperature of Beijing may be 50-70F. It is very comfortable for the hiking.
Train and flight are both available from Beijing to Shanghai. A high speed train ride should take around 6h and cost CNY550 for a second-class seat. The price of air tickets varies a lot in different period and the flight lasts for around 2h. If you decide to take a plane, it is suggested you book the tickets a couple of days in advance to get a discount. TravelChinaGuide can book tickets for you in advance. If interested, their contact information is bookingtravelchinaguide.com.