There are bullet trains among these cities. Train trip would differ a lot due to the train you've choosen. Bullet train is very fast, but the price is expensive. Some other ordinary trains has cheap tickets: there are CNY29 ticket between Hangzhou and SHanghai, CNY7, 14, 15 ticket between Shanghai and Suzhou.
You can buy tickets the time you arrive at there, for example, when you have arrivied at Shanghai Railway Station from Hangzhou, before you get out the station, you can go to the ticket office and purchase ticket for your leaving. For other occasion, you can buy ticket in the ticket offices in either railway station or ticket offices in town. Some hotel provide ticket service with certain surcharge.

For hotels, you need to stay over night at these three places respectively,
Suzhou: Motel 168 (Pingqi Road), near Railway Station
Hangzhou: Home Inn (Wen Yi Road), the city center area.
Shanghai:7 days inn, it has several branches, you can choose your location on their website.