Science

You can't compare a graduation level course and a post graduation course. Still, I will tell you it's you who will be paid, not your degree.
So try to be a better student and then think of salary. SRM will surely provide you a good platform but it's you who has to perform.

Yes you can do B.Sc. with 69.99%.
You are eligible.

The normal eligibility criteria for B.Sc. Math Honours degree course is a pass degree in 10+2 or equivalent examination in Science stream with at least 50% marks obtained by candidates in Mathematics subject or in aggregate from a recognised board or Institute. Check the list of all B.Sc. In Mathema

Please check for your eligibility for a PG course in Forensic Science from the criteria mentioned below:
Eligibility for PG in Forensic Sciences:
Minimum eligibility criteria for PG in Forensic Science course may vary across institutes. Primarily, the criteria include:
Bachelors degree in science/ engi

Home Science can be included in best four subjects % but they will deduct 2.5%. Or if you opt Bachelor of Science Honours in Home Science then only they will not deduct 2.5%. And every college have different cut off for different course.