Transportation from Dongzhimen to Park Plaza and how to reach Jinshanling

We will be staying at Park Plaza in Beijing on Sept 27. We have couple questions:

1. How do we get to the Dongzhimen bus terminus from Park Plaza?
2. Do we just need to arrive at the bus station and purchase tickets?
3. What bus number will we have to take if we want the special tourist bus leaves from Beijing at 07:30 and back to Beijing at 14:40?
4. Does the bus leave at 14:40 from Jinshanling or do we arrive at Beijing by 14:40?
5. Is Simatai Great Wall closed still? Since this is closed, how much time can we hike around the Jinshaling area?