I am a Italian citizen and planning to apply chinese visa in Hanoi. Is it possible to get it there?

It’s possible for you to get it there. If you apply for tourist L type, you need to provide your passport and its photocopy, the application form, a passport-sized color photo, and proof of transportation and accommodation arrangement. And then go to the embassy of PRC to hand in the application to apply for it.

Where to pay for visa tourist? In consular or bank? I need US dollars?
Thanks

You should pay for it when you collect it at the embassy. You may need US dollars to pay for it.