MDS

Among the most required Indian MDS professionals is UK. In coming years they have plan to recruit 6000 Indian Medical Professionals including Dentists. Second option Gulf where you get higher & tax free salaries. Thirdly in China where salaries are quite high.
There are good job opportunities for MDS in India as well in abroad. You have following options-
1) Lecturer/Tutor
2) Specialist
3) Short Service Commissioned Officer with the Defense
4) Researcher

You haven't mentioned the name of the city or district. Kindly let us know your locality so that we can guide you accordingly.

If you hv mbbs from india, you can go ahead with md from US as it will add new dimension to your career because of the rigour it requires. MD in india is equally competent though.

mds is more benificial

Yes, USMLE will be required for international students irrespective of the country you do your MBBS from.

Kindly go through The American Medical College Application Service (AMCAS) is a non-profit, centralized application processing service for applicants to the first-year entering classes at participating U.S. medical schools.