2. Taiwan and Taiwanese allies also have agency. China doesn’t just get to fire 20-30k ballistic missiles at Taiwan with no consequences. The consequences would maybe be asymmetrical, but they’d no doubt be very painful for China.
China is constrained on this by near certain mutually assured economic destruction.
Even the food supply in China would basically be destroyed unless you believe that the population is going to just go back to a diet of largely rice with meat being a luxury.
20-30k ballistic missiles at Taiwan would cause a global depression that dwarfs the great depression. There would be almost no way the CCP survive this. That is why this subject is mostly people talking nonsense.
Reunification has to happen politically, persuasively, over time and without firing a shot.
2. Yeah, dunno about that, who will do what exactly to China? I also think that, since you mentioned it, Japan would intervene, China will pretty much use it as an excuse for retribution on what the Japanese did to the Chinese during WW2.