Yes, Oppo A5s does have a 3.5mm headphone jack.
Yes, you can play PUBG on Oppo A5s. We recommend you to buy 4GB RAM variant of Oppo A5s for the better gaming experience.
No. Oppo A5s does not have the IR (Infrared) sensor.
Yes, Oppo A5s does have the fingerprint scanner. It also has the support for the face unlock.
No. Oppo A5s does have the fingerprint scanner but it is not the in-display fingerprint scanner. It is placed on the back side of the mobile.