2. After coming out from the north gate of Beihai Park, walk along the river and you can walk to Xie Jie, Dai Yan in about ten minutes. After Xie Jiechu from Dai Yan, you can walk to the north exit of Nanluoguxiang, about 15 minutes. After coming out of the south exit, you can walk to the west for about fifteen minutes and then return to Shichahai. You can see the night view of Houhai Bar Street and then return.
3. I suggest to look at Shichahai's website before coming, which is quite complete. After coming, go to the Beijing Tourism Consultation on the east side of Little Square in Qianhai, and get the map for free.
I hope this information can help you. Have a good time in Beijing!