Yes, Nokia 6 (2018) does have the Corning Gorilla Glass 3 protection. You can check this video, which is about Nokia 6 screen scratch test.
Yes, Nokia 6.1 (2018) does have the Carl Zeiss camera lens at the back.
Yes, Nokia 6 (2018) does have the OTG support.
Yes, Nokia 6.1 does have the optional beauty mode in the selfie camera.
Yes, Nokia 6.1 does support fast charging. During our tests, we have found that it took about 30 minutes to charge the battery from 0% to 50%.
At the end of the day, the Nokia 6.1 (2018) brings some welcome improvements over its predecessor.