New green card holder - filing US tax return for the first time

Hi there,

My father-in-law recently received his green card and entered US.  We are awaiting to get the green card (for both father and mother-in-law).  The are citizens of India.  All of their income is from India and they file and pay their taxes in India

1) When they file their US tax return - will they be able to get full tax credit for all the taxes paid in India (assuming there is such a provision in the India-US tax treaty)

2) Can the tax paid in India also be used to reduce state tax burden?  

3) They will be spending time in two different US states (California and Georgia).  How will this impact their state tax?  Would state tax be calculated based on the proportion of time spent in either state? (They are planning to spend approximately 6 months in US and 6 months in India)

 

Thank you for guidance on this topic!