Hi, Suugest you get to the ticket office of Civil Aviation Administration of CHina in Nanjing Road of TIanjin via the airport bus and then take the direct bus to Beijing Bawangfen Bus Station. Tian'anmen has tourist buses to the Great Wall. Some other places also have. It depends where are you leaving. Exciting shopping place, you can get to Wangfujing, Xidan. For Halal food, please refer to this:
https://www.travelchinaguide.com/cityguides/beijing/dinning/muslim.htm