1. An EMP would be an act of war. It would have no impact on nuclear weapons on submarines which would retaliate. Given that China has a dense population (high concentration, unlike the US which is spread out), China would lose. It also should be noted that throughout its history, China has never engaged in suicidal behavior. Indeed, China has never engaged in a war except against/in countries bordering on China.
2.It is unlikely a country would launch an EMP strike without a complete follow-up to at least strike at the other side’s nuclear weapons. The resulting radiation would minimize the danger of starvation.