Yes, the US sucks at winning wars. At the same time, I'm not sure what other nation is capable of waging war on the scale of the US. Perhaps the war on a large scale is just an intractable problem that cannot be solved, and the US is the only country that even tries. Not that I think that's a good thing. War in general sucks.
No, if you do a side-by-side comparison, China may do a good job of defending their region, but they would be completely unable to project their power or enter a different theater of war without leaving themselves defenseless. It's no contest at the moment. Besides the fact that due to its unfortunate foreign policy, the US also gets a LOT of practice waging war, where as the modern Chinese military has almost zero real-life war experience.
Neither side would win a War.. there would be no winners, just survivors, with both economies reduced to almost nothing, both population decimated both by direct costs and indirect( poverty, famine, etc) costs
No the idea that either China or America would "win" a war with each other is naive at best
