Efficiently travel to Great Wall, forbidden City, Tianmen Square and Panda Zoo within two days

My family and I gathered from Beijing International Air Port (PEK) at 1400 Hrs on Friday . We need to visit with our 2 kids for aforementioned places by using with suitable and reasonable travel mode such as sub-way, bus, and taxi services. Please guide us, from air port which terminal we have to arrive and out. The order of visit for above places such as 1st, 2nd , 3rd and 4th up to 1200 Hrs on Sunday. Because, on Sunday, we have to move to the train at Beijing Railway station. The Train will started at 1530 Hrs on Sunday.