Flying US to Singapore, then taking 30 day cruise on Holland America, ending in Shanghai. Need visa?

Your itinerary is eligible for 144 hour visa free transit under the condition that your flight from Shanghai to, I assume US, doesn't have any additional landing of any kind within mainland China and Japan.

- I'm not aware of the "self-help machines" at cruise terminal, but you should not worry about them because arrival/departure cards are relatively simple and they are usually dispensed on board the ship, so you will have your arrival cards filled out even before the ship docks in Shanghai. Here one additional information. Beside yellow arrival cards that you will, almost for certain, fill out on board the ship, you will also fill out the blue forms that are intended for those using 144 hour visa free transit. It is also possible, but less probable, that even this form will be dispensed on board the ship, but even if this is not the case, the best option is to fill them in the cruise terminal manually.

- You will inform your carrier in Singapore. There is no need to say anything in US because you will fly from US to Singapore and you don't need a visa for this portion of your journey, so US immigration will be uninterested about this. So, you will inform your carrier about this fact in Singapore, but you will, almost for certain, will have to tell then to the Japanese authorities too because you will have your last port of call, immediately before Shanghai, in Japan. You are advised to print out your flight ticket from Shanghai and to keep that printout with you. Also, you should have a confirmation of your accommodation in Shanghai because the blue form consists of several questions regarding your accommodation.