B.Arch

You can get a seat in NIT-Kozhikode, NIT-Trichy (less likely), RV College of Engineering, Modi University and BMS College of Engineering.

I think you should probably go for private universities like Amity University, Modi University, Manipal University and LPU. These universities have good placements.

Yes, according to your marks combined with your category, you'll definitely get into VNIT. Moreover, I would suggest you to go for better NITs as there are higher possibilities for them too.

You'll only get private colleges with this rank.

Enter your score and check here:
https://www.google.co.in/url?sa=t&source=web&rct=j&url=https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor&ved=2ahUKEwjUpLbay7bbAhUR448KHeU8DUkQFjAAegQICRAB&usg=AOvVaw1N9BzFtyUCP4JU-2UQHQ0H.

Admissions to B.Arch is based on NATA/JEE only.

Talking about best private architecture colleges in India, here is my list:
HZU (Himgiri Zee University), Dehradun
Aayojan School of Architecture
ACN College of Management and Engineering
Acharyas NRV School of Architecture
Adhiyamaan College of Engineering
Out of the colleges mentioned above, I think Himgiri Zee University as one of the best university for pursuing architecture. Their department of architecture offers an extensive study of design, planning and architecture. They provide the students with exposure to boost their confidence in the respective fields.