Science

It doesn't matter how many marks you have got. However, it depends on your preparation and understanding capabilities for each and every topic. Basically, in most of the cases 65% is the maximum score to apply for M.Sc course in any institute. If you have not applied for JAM yet then you can go through other entrance exams conducted by different universities.
You should try in top central universities like Hyderabad University, BHU, Pondicherry, Delhi University, etc. You can further go for CUCET conducted by 10 central universities.

You should apply for ICAR test.

Yes, you can get admission in a college for B.Sc in Semester 2. However, there are a maximum number of colleges which give admission in an odd number of a semester.
If any hurdle occurs for admission in your desired college, complete the semester 2. Afterwards, you can directly go to semester 3 with Lateral Entry in a college.

No, you cannot get direct admission in 2nd semester of B.Sc. You have to start from 1st semester itself.

For this, you can do a Bachelor's degree or even Master's degree on film production and all. Look for colleges which provide you with editing and stuff.

You have to go there on the basis of your class 10th basis. You could not get admission in polytechnic second year, you are even not a student of science.