BBfanboy is correct; I'd add that what Quiet China specifically does is disable the AI scripts for China which allow the AI to make significant initiatives (i.e. offensive moves). The AI will still defend itself and attack targets of opportunity as BBfanboy said.
The air war will still be active with the Japanese Army Air Force and Chinese/AVG units being the primary participants on both sides. You will still be able to ignore the air war in China if you really want to, although I'd recommend trying to fight it anyway as preparation for future campaigns. It will teach you how to build an air force and to operate with limited resources. It will also build your tolerance for not being able to be everywhere or defend everything at once. This is generally true of the entire Allied war effort early on, but it's especially acute in China.
Down the road (you won't be able to do much anyway early on), I'd recommend not making any serious offensives in China as it will give you a false sense of the situation with a hamstrung AI - such as pushing the Japanese back to the sea or taking major objectives (Hong Kong, etc.). That said, I'd recommend making limited offensives so you will get an idea of how much supplies can be consumed by them as well as practicing ground operations in general; that is, getting a feel for the effects of disruption, supply, HQ organization, etc.
Also use China to practice logistics. Set up the supply flights from Burma 'over the hump' into China. Figure out how to get pilots trained and the squadrons configured so as to manage fatigue and loss of airframes. Practice building infrastructure selectively, as each new airbase/port/fort you decide to invest in sucks up the precious supplies you are trying to bring in. Note how supplies flow through roads/railroads. The China/Burma/India theater in particular has isolated road/rail networks, so you have to pay attention to where the supplies will come from and where they will flow to without your intervention.
Finally, I highly recommend taking a look at Kull's 1st turn spreadsheets. I followed them completely for my 1st turn, and by the end of it I knew the game well enough to proceed on my own. You don't have to follow the speadsheets to the letter, but they will help keep the momentum going when you are overwhelmed with choices. You can sort the spreadsheet by regions to make it easier to digest. The 1st turn is especially brutal in terms of player input - it takes much, much longer than your typical turn because you have to overcome the inertia of getting the 'ball rolling' on everything; this is true even for veteran players. The following turns become much easier as you only need to give input to a fraction of the units - those that are new arrivals, have reached their destination, engaged the enemy the previous turn, etc.
EDIT: Also take a look at the Useful Info for Beginners when you feel lost. Also download the forum squeeze PDF file.
< Message edited by Korvar -- 4/6/2018 10:06:12 PM >