1. Whether the Indian Marriage is still valid since the second marriage was done in Us tothe same girl.
If the marriage with the girl was solemnised in India as per Shariat laws, then the marriage with the same girl in US is invalid, becasue as per Shariat law, a married woman cannot marry again during the subsistence of her previous marriage, even though it is the same spouse.
Therefore the subsequent marriage can be termed as a customary function o0nly instead of a valid marriage, hence there is no need to dissolve that customary function.
2. Can the girl take khulla under the Indian Islamic act
She and her spouse can decide to dissolve their marriage by mutual consent which is termed as 'Khulla" and it is acceptable as per Shariat Laws in India.
3. Can the Us marriage be nullifed under exparty.
Read the answer given in the first above