From Hangzhou Railway Station to Leifeng Pagoda

To Leifeng Pagoda:
1&2. Yes, you can take line Y2 and get off at Jingsi with CNY2. Then you can see the pagoda. This is the best bus choice.
3. The regular Shanghai Smart Card cannot be used on buses in the city.
4. Local Transportation Card can be used on line Y2.

To Longxiangqiao:
1. Bus line Y10 is right. You should get off at Dongpo Road Pinghai Lukou and walk to Longxiangqiao.
2. Bus no. 7 and 51 can also be of use. However, you need to walk 10-15min to Xinxin Fandian bus stop to take them. So Y10 is the best.

Have fun!

Thank you for your advice, however, can you give me more info?

From the Main Railway Station,
1. Which bus stop for waiting bus Y2, near exit A1 or A3?

From Solitary hill to Longxiangqiao
1. How much is cost of bus Y10?
2. How much is cost of bus no. 7 and 51?

From the Main Railway Station: you can take bus line Y2 from Chengzhan Railway Station. It is adjacent to Exit A1 of the metro station. You will easily spot it.

From Solitary Hill: the bus line Y10, 7 or 51 costs CNY 2 per person. :)