You should prepare HK Dollar in Hong Kong and Macau, some small bill will be helpful. In Shenzhen and Shanghai, only Chinese RMB is accepted. The international Credit Card of visa, mastercard and China UnionPay could be used in all of these cities.

The electricity of HK and Macau is 220V, using Britain standard socket. Shenzhen and Shanghai use the international standard electricity of 220V. Usually, these hotels do supplies free electric power convertor.