Diploma

Yes, you can. I am also pursuing the same from Chandigarh University.

You should opt for M.Sc in biotechnology. It would be a much better choice.
Well, M.Sc in forensic science is a better option than Diploma in forensic science.
Good luck.

You should take admission in B.Tech after diploma through lateral entry. Select CSE/IT branch.

Going for Diploma is the best option, as you get a great practical knowledge in your field. But, now a days, select college as per acknowledging that college teaches you something else in practical knowledge.

You should take diploma engineering in CSE.

No. In AMU, mode of teaching in diploma course is only english. However it is not too difficult for Hindi or Urdu medium students. So, do not worry about it. Once you qualify the entrance, language will not a bar.

You may get admission after completing your diploma if you will secure good ranks in JEE Advanced. To appear in JEE, you should have 75% marks in your diploma or intermediate (the percentage may subjected to change in coming years).