Certification

B.E. is more recommended as it provides more in-depth knowledge of computer networking and the way a computer and the networking system work. This serves as the foundation for CISCO certification courses. Comparatively, BCA doesn't provide the details to such an extent. That's one of the reasons why MCA is considered equivalent to BE and not BCA.
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To attain an associate's certificate in this field you need 2-3 years. Whereas, the undergraduate Bachelors degree in interior design takes 4 years and 2 years for Masters.

You can pursue AUTOCAD, SCADA and PSWORLD course.

For gaining admission to an MBA program, it will not be of much use. But this will be an added advantage for your CV, if you do MBA in finance.

Nothing will happen with that certificate. If you want to become an IAS, you should appear for civil services exam which UPSC conducts every year (IAS is all about administration, how can you think that c+ certificate will be useful for it.).