Colleges in Gujarat

Architecture does not have placements, you have an internship in your last year, you may continue with the same firm or apply to some other firm. An architects career opportunities vary such as
Entrepreneurs
Architects (Junior/ Senior)
Furniture design
Photography
Construction& Community based volunteering
Infrastructure development
Graphic design
Set Design
Jewelry design
Advance research in Architecture
Faculty @ School of Architecture
History, Restoration and Preservation
Interior design
Product design
Landscape Design
Project/ Construction Management

birla vishwakarma mahavidyalay is older college and may be better. it is also located near engineering industries.

There are usually two ways, by taking CAT and then WAT/PI. For second one, if you have lived outside India for at least 18 months and are away during CAT examinations, you can apply to IIMA using your GMAT Score. There is separate process for that.

IIM Lucknow is behind IIM Ahmedabad, Calcutta and Bangalore in rankings.

I can't say about other college but try for B.K. School of Business Management. You have good chance of getting into bk. Last year till 70 percentile students with SEBC got admission in this college. So you have a bright chance.