Job offering in Hai Phong

I am a US citizen.  I had an offering in Hai Phong that the company pays my monthly salary via a holding bank in Hong Kong.  Along with salary, they will provide local health insurance housing and driver etc .  I don't want to move to Hai Phong permanently.  Currently, we have agreed that I will work in Hai Phong two months and working in the US 1 months... the rotation will continue like this basically every quater.  Company will pays for my economy ticket each time.  I am totally new so give my ignorance or etiquette.  Here are some questions and hoping expat experts can help:

1.  With current work schedule stated above, is this mean I am a residence of Vietnam or non-residence.  Is there a work around for this residence or non-residence i.e businsess traveling.
2.  If I am qualified as residence/non-residence, I am assuming that I will subject to local taxes, right?
3.  Follow up with question #2, this mean I can not file for FEIE (Foreign Earned Income Exclusion), correct?
4.  If question #3 is correct, is this mean I have to pay double taxes?  Any work round this? 
6.  Any local tax accountant in Hai Phong you can recommend?

Thanks in Advance!