West Bengal

Total expenses will be around 1.4L for 1 year.

Please visit this link. This is a college predictor by Shiksha and I hope this will help you to choose the right college-
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor&ved=2ahUKEwie-7mvrITiAhWz73MBHYuID8oQFjAAegQIAxAB&usg=AOvVaw1N9BzFtyUCP4JU-2UQHQ0H.

Yes of course,
You will get admission in this College with the Grade you have.
You have options for B.Com in Accounting and Finance, and Bachelor of Management Studies (Honors).
If you wish to pursue MBA, go for BMS (Honors), if you wish to pursue Masters in Economics, B.Com would be a better option.

Hi,
There are a lot of good colleges in Kolkata. Check for the Council of Architecture approved colleges in Kolkata. Check the link below to get a list of approved Architectural Colleges. https://www.coa.gov.in/index1.php?lang=1&level=0&linkid=25&lid=26.

Kindly specify your location as you haven't mentioned anything in the question neither tags.

Of course, you can get admission into any top college, because class 12th percentage doesn't matter and all the reputed college has entrance exam.
I hope, you did well in your entrance exams. Never lose hope. Even if you couldn't manage to grab a seat for BBA, then try and make your goal to crack any competitive exam for MBA, because what matters is the position you reached at the end and not what was beginning you started from.
All the best.

Yes, you can get a direct admission, just look for a best college and apply for further procedure. All the best for your future.