may I pay a taxi with my debit card ? one said as a foreigner I will pay much than a chinese , true?

Bertrand, generally speaking, you can't pay a taxi with your debit card, but you may pay by Alipay or Wechat. Some drivers may charge more to foreigners, but this is a breach of the rules. Actually, you can just tell the driver to run the meter to calculate the fare for you.