Diploma

You have to give IELTS/TOEFL exams, but chances are not very high that some university will accept your application.

Hello,
You can go for one year of Diploma. These vary between study programs and levels. For each course, Indian students will need to meet a minimum English language requirement. Along with that a minimum academic record of 65% and above in class XII will be required. Foundations and Diploma program

Yes, you can apply for MBA. MBA is a post graduate programme, so since you are a BE you can apply for admissions. However, you should have scored more than 50% marks at graduation level exam.

Yes, you can get admission for Diploma in food technology.

Yes, you can do so, only in some limited branches. Such as from IGNOU Indira Gandhi National Open University (New Delhi-110068) - Vertically Integrated Engineering Programme and Advanced Diploma leading to B.Tech (Civil) - Branches: Construction Management, Water Resources Engineering.

Yes, you can get. Please apply through State Common Entrance Test Cell, Maharashtra State by using official website http://cetcell.mahacet.org/
Click on direct second year engineering (DSE) tab for registration purpose.

Executive MBA is often offered to professionals who have worked in managerial level for 4-5 years. And, Diploma is not equivalent to a Bachelor's degree. You need a Bachelor's degree to get admission in MBA programs.

Use this college predictor for MHTCET college prediction. Here, you will get information about in which college chances of your admission are high:
https://www.shiksha.com/college-predictor

Yes, there are plenty of colleges in UK offering Diploma and PG Diploma to international students. Choose which subject you wish to study and the check for colleges.