Nokia 1 is not completely metal body. It has metal chassis frame and the housing is made of polycarbonate material.
Yes, Nokia 1 does have the wi-fi hotspot.
You can record 720p resolution videos from Nokia 1.
Yes, Nokia 1 does have the Google Assistant in-built.
The Nokia 1 is an inexpensive Android smartphone, and as you can tell from the Nokia 1 review, you very much get what you pay for.