B.A

Yes, IASE deemed university recognised by UGC and AICTE. So you can pursue your studies from the same. It is valid for the government jobs. Source: http://entrance-exam.net/forum/general-discussion/iase-deemed-university-valid-university-government-job-816666.html#ixzz691G695Z1
Yes, Distance education applicable and accepted in government. Organizations. The institute that you will select to pursue the course will have an impact on the acceptance of your degree. You can pursue the degree / Diploma / Certification from UGC, DEB & AIU approved university.
You can do your research on various institutes like MITSDE, NMIMS, IFIM, XLRI, IIM-C, and others before enrolling and arriving at a decision.

As a part of course we all had six semester and out of those six we had mathematics in four semesters. I will give my opinion in two parts, namely mathematics and other subjects (theory). Separate because I was good with mathematics and moderate with theories. For mathematics:
You will get marks for each and every valid step. No matter you reach final solution or not provided you are solving in the right direction. For other subjects:
What I think is, it totally varies with different exam checking examiner. I was not among those who were good with their writing skills. I used to write answers to the point. Still managed to get passing marks (more than 60% at least). And why I said it varies with different examiners, cause there were situation when I wrote very less in theory exam and got more than satisfactory score on the other hand when I wrote theory exam more than required (you prepared most of those questions in the last 4060 hours) you go straight to the examination hall and fill sheets cause you know that answer (no body can actually stop you from writing).