I am a J1 Post doctoral fellow who will start working in a University lab in the US from March 1, 2011. I am Indian citizen but have been residing in Germany for the past more than 4.5 years. I have paid income tax in Germany for about 4 years. I still have German resident permit for another 15-16 months.
I would like to know:

1) As I was a resident of Germany and not India, even though I am an Indian citizen, can I claim tax exemption under the US-German treaty? If so, what documents would I require from Germany to make my claim?

Yes, you can. Your are counted as the tax resident of wherever you have worked 365 days prior to your arrival.