Hi, for your visit in Shanghai, you should not miss the Bund, Yuyuan Garden, Jade Buddha Temple and Shanghai Old Street, Shanghai Tour(https://www.travelchinaguide.com/package/shanghai.htm) offered many tour packages as well as itineraries and destinations suggested. The avarage temperature would be 18-23C if it is sunny, might get colder if it rains, better notice the weather forecast before coming. For plane ticket, you can search at this website China Flight Tickets(https://www.travelchinaguide.com/china-flights/),there are discounted tickets, better book ticket in advance, the earlier you book it, the cheaper it is.