那我在美国的payroll 和insurance 不受影响吧 -It is irrelevant. As long as your employer pay you and you pay the premium to the insurance company, you will be fine.
如果居住不到180天 我来年的税怎么报呢。-Your income is got in China even if you work for a US employer and thus, technically you do not need to pay the income tax to US Government (IRS), but pay it to the Chinese Government because you are not a green card holder or US citizen yet.