Yes, its 20mm focal length is widely considered the 'sweet spot' for vlogging, offering a wide perspective that includes the environment without the extreme distortion of wider lenses.
No, it does not have built-in Optical SteadyShot (OSS). It relies on the In-Body Image Stabilization (IBIS) found in most Sony Alpha camera bodies.
The lens uses a standard 67mm front filter thread, making it easy to attach ND or circular polarizer filters.
Yes, it fits perfectly on APS-C cameras like the A6400, providing a 30mm equivalent focal length which is excellent for street and general photography.