M.A Hindi

It depend on the universities procedure. Which university allows you to do MA Hindi based on your graduation in other streams.

The first and basic qualification required for a Ph.D. course is that
you must have completed your Masters degree course.
To apply for Ph.D. you can either directly apply to the professors of
different universities sending them your resume , Statement of purpose
and your research papers. Or you can appear for UGC-NET examination
and then sending your NET scores to the professors under whom you want
to undergo your Ph.D. course.

Yes, you are eligible for the same.

Yes, you can pursue both the courses.

Yes you can and you can opt for jobs after that

MA is a degree you can get by studying in two ways. One is full time or class based and one is distance learning. However, one can do MA in any domain in distance learning and they can appear for M.Phil/PhD. Since these two are also degrees you can earn by joining into those fields. Where as PhD is the highest degree qualification for a person to learn and to create knowledge in the field one will go for research.
So you are eligible for PhD after completing MA. I hope that above information will help you in one way or other. Have a good time!