Cruise to Shanghai ,stay 3 - 4 days, visa needed?

please tell me, we are interested in taking a 28 day cruise that stops in Singapore, hong kong, vietnam, india, Xiamen, china, and ends in SH, china for 2 days. we want to stay in SH an additional day or two. do we need a visa for these places? we are from the USA - only 2 people and will be on our own touring. thank you kindly, edie (only 2 days maximum in the places mentioned above on a cruise)