On your first bullet regarding free hotel night in Shanghai, even if it would be offered by the airline I would not rely on such a solution. Although not having first-hand experience myself, I have read many reports stating that the hotels provided are crappy and if you are travelling solo, you might even have to share your room with a stranger...

Moreover, even if your ticket would be eligible to STPC service, the fact you bought your ticket through an OTA could raise some issues for MU (I have had troubles myself booking a free transfer service from CDG having booked a ticket through an OTA, the ticket departing CDG being issued from the Netherlands and not France... but eventually managed to have the service booked nonetheless).

On the other points, I would be more confident but expect the airline to send you back to your OTA to arrange rebooking.