Science

B.Sc (Hons) Chemistry is a sufficient qualification to seek admission in M.Sc forensic science. Exposure on Bio-Tech and biology subjects will help you to become a forensic scientist.

Actuarial Science is a mathematical science and not a medical science. For more details visit www.dsacted.org.

Let me clear your doubt that B.Tech is fully a professional course & CS in it is much better than CS in B.Sc. So I'll suggest you to go for it.
Moreover, all the central institutions like NITs, IITs, IIITs, Central Universities, etc. are good to study at. In addition to it, certain other are also good like D.Y. Patil, BITS, etc. But what you choose completely depends on you. It depends on how you can go with B.Tech's challenging study curriculum, the study environment of the educational institution also is important. Give importance to all and decide finally. Best of luck.

R.D Sharma & R.S Agarwal are the best books to start with for entrance preparation. Its clear concepts in simple English should always be in verse with. After that, if you desire to get above 170, you need a planned study with the help of coaching for the entrances. Moreover, the schools are also very important to clear your doubts.

It's better for you to pursue post graduation in IITs because the tag IIT graduate has always standard demand. You need to appear in GATE in order to get admission in IITs.

I think you can't do it because for UPSC exams, graduation is compulsory.

If you have selected computer subject in your 12th then you have a chance to do B.Sc in computer science.

The fee is approximately 2 lakhs for first year.