Yes, you can record 4K videos from Galaxy A8 Star's rear camera. From the front camera, you can record up to Full HD videos.
Though Samsung has not confirmed about the Corning Gorilla Glass support for the Galaxy A8 Star but we suggest you to check this video to know how durable display is.
Yes, Samsung Galaxy A8 Star does have the support for the portrait mode.
Samsung Galaxy A8 Star comes with 9W / 1.67 Amp charger. It has a USB Type-C port and charges quickly.
Yes, Samsung Galaxy A8 Star does have the 3.5 mm headphone jack.