Which type of Hangzhou transportation IC card to use?

I have read the article but to confirm. I plan to stay in HZ for 3 nights, and to rely on the metro and buses; no need for bicycles. (a) Should I use T or Z card? (b) Can I purchase either card at the metro station of the Main Railway Stn (Chengzhang)? (c) Or, should I pay cash for each trip I make?