Hi I am at Huixin East Street near the university of international business and economics

1. You can take bus No.684/674 from UIBE Station to Huixin West Street Station, then transfer to metro Line 5 to Yonghegong Station, next transfer to metro Line 2 to Xizhimen Station, and finally transfer to metro Line 4 to Dongwuyuan Station(Exit B).
2. It can be bought online in advance, but I think it is difficult for foreigners because the booking page only has Chinese version. So you can buy it on the spot.