Fare is 70RMB ($10USD) for second class, 113RMB ($15) for first class, and 213RMB ($30) for business class
You can get to the Hangzhou East Railway Station on subway line 1 (the red line). It's about 30 minutes ride from the downtown/West Lake area
There are enough trains that you don't have to book the tickets in advance. Just go to the station and buy a ticket at the counter. You'll need your passport to buy train tickets by the way
You can use Ctrip.com to look up the current train schedule. Trip.com is the English version of this site, but I can't seem to find Qiandao Lake in its database. So for the time being you just have to rely on Google translate and the Chinese version of Ctrip to find the latest schedule
Getting to the docks from the Qiandao Lake Railway Station
Option 2: Take the big blue bus (either route 001 or 002) to get to the hotels and docks area. The blue buses are dedicated buses transport people between the hotels and the railway station, and the trip takes about 40 minutes. I believe the fare is 15RMB for the blue buses.
Option 3: There's also a black bus that gets you to the North Bus Station, which is close to all the hotels. From here you can then take public bus K015 to get to the docks (well it drops you about 400 meters away from the docks). This option takes about 1 hour and costs 6RMB in total.