Untested does not mean ineffective. And in the context of large-scale operations against a symmetric foe, the US Navy is almost equally untested. Their stand-off missions in Afghanistan and Iraq hardly count. China conducts large-scale exercises, and so do we. Whose models are the more effective?
They have a substantive submarine fleet capable of launching both nuclear ICBMS and tactical weapons. It is true that the majority of their submarine fleet uses diesel-electric propulsion (though they do have a small contingent of nuclear-propelled subs), however these subs are as quiet or quieter than nuclear versions, and in the context of carrier-group escort and local ASW operations, equally effective.
Very true. However, they are developing tactics for 21st-century conflicts. Our carrier tactics are largely based on what we learned from WWII and the Cold War, and it is unclear how appropriate those doctrines are.
Compared to our subs though they are noisey. We can commit forces to sinking the Chinese navy and would very likely do it with a minimum of losses. China won't retaliate with nuclear weapons as they know ours are larger and far longer range and they'd loose any diplomatic channels.
China is on its own they have no serious strategic partners while the us has the NATO of the Pacific with the big players being Japan, Philippines, South Korea, Australia, and US Pacific Command. Australia being an ally guarantees the Commonwealth countries would intervene so Canada, India, UK, ECT would all come to aid Australia in a war and Australia has no interest in China becoming dominate in the region. The deck is stacked agasint China.