Institute of Chemical Technology, Mumbai

In M.Sc, one has to chose only 1 subject. If you want to do M.Sc in chemistry, then you don't need to study maths.

No, you can get admission from one of them.

If you want to take admission in NIT/ IIIT / IIT /GFTI, then you need to qualify JEE Mains to get admission.

Minimum Eligibility Criteria for UG Courses:
Candidates need to be Indian nationals to be eligible to apply for admission in UG programmes offered at ICT.
Apart from this, aspirants should have cleared their qualifying examination (having science subjects) with atleast 50% aggregate marks if they are from General category. If the applicant belongs to categories like Backward classes and Persons with Disability then they meet the eligibility criteria if they have secured at least 45% marks. However, this percentage reduction would be offered to candidates belonging to Maharashtra State only.

I think no. For the year 2016, the government carried out admission by MHTCET as well as JEE Mains. 70% admissions of the total seats were carried out through MHTCET and the remaining 30% were done by JEE Mains.
A separate form is to be filled for admission through JEE Mains. Then the college puts up a merit list according to the scores in Mains and then a counselling round is done for filling up the 30% seats in each branch.

Food technology being a matured branch in India where a startup would be the right idea in my opinion. Or else one can work in a food processing company at the outset and learn all design and operational aspects. Placement-wise, ICT is very popular.

Yes, the forms are available online.
For admission details refer:
https://www.shiksha.com/b-tech/course/b-tech-in-food-engineering-and-technology-institute-of-chemical-technology-ict-matunga-east-mumbai-184387

You can get admission with both PCM and PCB percentage, whichever is higher. But there is around 3% relaxation for PCBM students.