Polytechnic

The only benefit that you will get is concession in fee. Except for that, there are no other benefits which you will get only in government polytechnic.

With what mode are you pursuing B.Sc. and diploma? If both are regular, then probably your B.Sc. Degree will be invalid or maybe both. Only that degree will be legal where you have given your Migration or Transfer Certificate. You should pursue B.A. Or BBA through distance mode to avoid any legal obstructions later.

Yes, it is approved by AICTE.

Not now. You need a graduation degree to appear for IAS exam. Diploma is not considered equal to a degree. You can, however, pursue B.A. or B.Tech after Diploma and then you will be eligible. You can also pursue a distance course with Diploma.

Not, yet. After completing Diploma or when in the final year then you can apply for Loco Pilot. Before that, you are not eligible.

Here is a list of good colleges in India offering Mining:
https://www.shiksha.com/b-tech/colleges/b-tech-in-mining-engineering-colleges-india.

MBA is a post graduate programme. So, you first need to complete your graduation & then explore pursuing MBA.

Hi Dev,
Today only, I went gov poly for admission regarding my sibling. So, there was written clearly Rs. 2504 DD for OBC/SC/NT candidate plus 3000 extra cash. Whereas Rs. 6000 DD, Rs. 2504 DD and 3000k cash for open student. This fee structure is from Nagpur gov poly. Here you can see OBC student don't have to pay extra 6k. So, OBC student is getting concession as compared to open student.
Regards.

Hi,
You can pursue distance education ITI Diploma in RAC from Tamil Nadu Open University, Chennai.
Thanks