Yes, Samsung Galaxy A8 Star comes with a hybrid sim slot. In addition, the phone also has OTG support.
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.
Yes, Samsung Galaxy A8 Star does have the face unlock. In addition, it also has a fingerprint scanner.
Yes, Samsung Galaxy A8 Star does have the support for the portrait mode.
Yes, You can record slow-motion videos from Galaxy A8 Star.