As an American, I had a great time living and working in Hong Kong for 6 years.
You need to go do some serious reading before talking to anyone. One person in HK wanted me to pay them US$2,000 to do my relatively simple taxes. A CPA in the US can usually do your taxes for a lot less than that, even after using the overseas express mail a few times, but if they don't do these regularly you may want to be able to detect that and/or be able to point them in the right direction.
There is a Foreign Earned Income Exclusion that could allow you to eliminate ~ $80,000 a year from your income for US income tax purposes on the grounds that you live overseas. The reason this exists is that the US Government realizes that the foreign country has their own taxes that you will be required to pay because you live there under their laws. In my case, my employer was foreign, and I had a foreign address where I lived year round, and my only US address was a relatives' address who forwarded mail. So for the US authorities there weren't any murky issues.
One way to make sense of all this is to consult the source directly:
where you will find this interesting paragraph from the IRS website when you click on the link on #1 Do you have Foreign Earned Income?
Source of Earned Income: The source of your earned income is the place
where you perform the services for which you received the income.
Foreign earned income is income you receive for performing personal
services in a foreign country. Where or how you are paid has no effect
on the source of the income. For example, income you receive for work
done in France is income from a foreign source even if the income is
paid directly to your bank account in the United States and your
employer is located in New York City.
After some interaction with @littleadv, I decided to post the rest of this section from the IRS website, so you can see exactly what their examples say.
If you receive a specific amount for work done in the United States,
you must report that amount as U.S. source income. If you cannot
determine how much is for work done in the United States, or for work
done partly in the United States and partly in a foreign country,
determine the amount of U.S. source income using the method that most
correctly shows the proper source of your income. In most cases you
can make this determination on a time basis. U.S. source income is the
amount that results from multiplying your total pay (including
allowances, reimbursements other than for foreign moves, and noncash
fringe benefits) by a fraction. The numerator (top number) is the
number of days you worked within the United States. The denominator
(bottom number) is the total number of days of work for which you were
Example: You are a U.S. citizen, a bona fide resident of Country
A, and working as a mining engineer. Your salary is $76,800 per year.
You also receive a $6,000 cost of living allowance, and a $6,000
education allowance. Your employment contract did not indicate that
you were entitled to these allowances only while outside the United
States. Your total income is $88,800. You work a 5-day week, Monday
through Friday. After subtracting your vacation, you have a total of
240 workdays in the year. You worked in the United States during the
year for 6 weeks (30 workdays). The following shows how to figure the
part for work done in the United States during the year. Number of
days worked in the United States during the year (30) ÷ Number of days
of work during the year for which payment was made (240) × Total
income ($88,800) = $11,100. Your U.S. source earned income is $11,100.
These calculations are typically for US persons who have taken a long-term job assignment and really do live a foreign country. Generally it is expected that they can prove that they live in the foreign country (have a home or flat), or were physically there (from, say, passport stamps) 330 days per year. If neither of those apply, the
FEIC doens't apply. So there is no ~$80,000 relief for a US person who works in Australia for 3 months. However, while the FEIC isn't available for short foreign jobs or occasional foreign assignments, there may be other forms like the foreign tax credit, that do still apply. But they only apply to the extent you owe and pay taxes to a foreign country, so there is no free lunch....
None of this magically gets a person out of paying taxes.
Also, see IRS Publication 54, Tax Guide for U.S. Citizens and Resident Aliens Abroad.