Diploma

You must go for civil engineering programme directly
As basic eligibility for civil engineering include:
10+2 Science with Physics, Chemistry and Maths is mandatory for admission to a course in Civil Engineering. Entrance Exams (IITJEE, AIEEE, BITSAT etc. ). Are conducted at both the national and state level. Diploma course for the position of junior engineer can be taken up after Class 10.

hey,you must have 50% aggregate marks to be eligible for cpl and you need to clear class 2 medical class for the eligibility as well

Check your desired programme specific requirements firstly, decide accordingly. MS admissions are very tough in Canada. If you have excellent academics you may complete a relevant PGDM and apply for MS or better you. Apply for PGDM in Canada. Also see that you have some solid projects and internships, publiacations etc. Before applying for the MS.

PGDM is valued in Canada, its a professional job oriented degree. Also, you can apply for a work permit after your PGDM. However if you want to come back to India you must gain some excellent work experience there or perhaps another degree like an MBA.

It all depend on you, if you quit the Polytechnic course, then you have to do your class 11th and class 12th for further graduation studies. And, you will be starting your graduation from 1st year, but if you complete your Diploma, then you will get admission in 2nd year of graduation course. Thank you.

Yes, it is a Diploma course.

Technically, you can do a Masters if you have Bachelors. But, when you apply for a Masters in fashion design the requirements are to submit a portfolio. These portfolios are really elaborate. For example 12 garments designed and sewn by you. Fit on a model with pictures taken, etc. Also, there might be a design challenge. So, if you have your portfolio you can surely apply for M.Des.

https://www.shiksha.com/college/m-h-saboo-siddik-college-of-engineering-byculla-Mumbai-20534/admission
May this help you.