Dear - I need informations about subway

As I know, the nearest subway station to your hotel is Dengshikou of line 5.

You can take airport express and transfers to line 2 at Dongzhimen, and transfer to line 5 at Yonghegong, get off at Dengshikou from Exit A.
After that, you can take a taxi to your hotel, since it’s about 1.3 km far.

As for train to Great Wall, I happen to know train S2 goes to Badaling Great Wall, and you can take metro line 5 to Lishuiqiao, and then transfer to line 13, get off at Huoying from Exit G4. Then walk east to Huangtudian Station to take train S2 to Badaling.