Hello

JEE Main paper 2 also known as JEE Main B.Arch Examination is for those candidates who aspire in the field of Architecture. It measures the aptitude of the applicant for Architecture. The test measures drawing and observation skills, sense of proportion, aesthetic sensitivity and critical thinking ability, that have been acquired over a long period of time, and that are related to Architecture.

No. One need not clear JEE Mains Paper 1 to get admission into B.Arch / B.Planning in NITs and CFTIs.

On the other hand, you don't need to appear for JEE -Main paper 2 in order to qualify for architecture at IITs.

You just need to appear for JEE Main paper-1 and need to qualify it. After qualifying for JEE-main ,one need to appear for JEE advanced exam. After qualifying JEE-Advanced, one need to appear for a special test called AAT (Architecture Aptitude Test) for getting admission in architecture department of IITs.

I hope it will help you
Good luck...