Hey there, PAC-MAN79,
Thanks so much for using Apple Support Communities.
In order to save photos from the Files app to your Photos app, you would simply want to select the photo (or photos) in the Files app, tap the Share icon and choose "Save Image". If you'd like to select more than one image at a time, you can tap the "three dots" icon in the upper, right hand corner of the Files app and choose "Select". From there, tap each photo you'd like to save and repeat the steps above starting with tapping the Share icon.
With regard to metadata, there isn't a way to determine what type of information gets saved between the Files app and the Photos app. However, you can always edit things like location and date for each photo directly in the Photos app by following the information in this article: Edit photos and videos on iPhone - Apple Support
We hope that this information is helpful.
Have a great day!