1. If you want to change Hong Kong dollars, a small amount of Hong Kong dollars is ok. It doesn't matter where you change, but you'd better not cross the gate, especially near the subway station. It's too dark. Generally, it's good to buy things with UnionPay, and there is no handling fee (except for small shops, such as pharmacies). Sasha and Zhuo Yue can brush UnionPay;

2. You only go to Mong Kok East, there is no need to connect all day, so you will lose money;

3. Any exit in Mong Kok East is the same, but exit C and exit D are recommended. Besides, I'm afraid you won't leave. Exit C is opposite the bus stop, and the exit is slightly to the right. Go downstairs in the new century, get off the elevator and take the overpass. There are instructions at the top of the road (Mong Kok Station, direction of Garden Street). Garden Street is next to the overpass on the left, which is Xiebo Street. The next exit is Xiyangcai South Street, Shasha, Zhuo Yue, Huaruntang, Wanning and Watsons. Exit D goes directly into the new century, and there is a shop above you. The following is under renovation. I don't recommend you. Same as exit c;

4. You don't have to go the same way. There are shops everywhere around here. Then ask someone else. If not, take the Guantang Line (Tiaojingling direction) at Mong Kok Station to Kowloon Tong and then transfer to east rail line to Luohu.

5. Tips: Starting from Luohu, it is best to take the bus at the end (by the direction of the pass) and return to Shenzhen, and it is best to rely on the front (by the direction of the car). It's convenient to leave the station at the rear, and the front of the car is crowded for a long time, which can save you at least half an hour.

I hope the above answers can help you.