In order to avoid U.S. income taxes on a total annual salary, excluding per diem, of approx $88,000, after personal exemptions and deductions your adjusted gross income would be about $80,000, you would have to stay outside the U.S. and its territories for a total of 330 days per year. You are liable to pay taxes above that amount.
www.irs.gov has a thorough, detailed analysis in qualifying for foreign tax exemption. Generally, If you are a U.S. citizen and you report for work in the USA, [flying into and out of USA or flying domestically] you will be subject to income tax, no matter where you reside.
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