Re: career path suggestions?
Generally, for religious students the career options seem to be teaching, being imam/scholar, and/or running small business as a secondary mean for earning. But since you are not interested in teaching at this point (and of course you need to study more to become a teacher, specially for higher schools), other option come in my mind are:
Continue for MS and PhD for sure, since you have the blessed stamina of studying more so make the most of it. Real learners never stop studying even after PhD, and that's a good thing.
Since you wanna do da'wa work as well, one way is through 'writing'. You can be a writer (not suggesting full-time though) - writing books as well as articles for newspapers, etc. You can take short-courses to improve ur writing skills to be a professional writer. Your language skills could be handy here too, for example, you can be a correspondent of a news media (say jang group) and monitor Arabic, Hebrew, German and French news sources and write for your employer - which comes down to Journalism.
Another option could be a Librarian. Well, that'd keep u close to books and you can do research work as well. I believe for becoming a scholar, a religious teacher, a writer and a journalist you need to read a lotttt.
As far as making difference to the system (in Pakistan) is concerned, i think that's a huge task. Education system that is being dictated by super powers, can't be changed by common people. However, you can contribute to the limited extent for sure, in different ways. There are many NGOs working on different issues, you can join any or start your own. Atleast something is better than nothing ........ just my two cents (fi sabilillah :p )