No, the Sony SEL50F18F does not feature official weather or dust sealing. It is recommended for use in dry environments or with a rain cover.
No, this lens does not have built-in Optical SteadyShot. It relies on the In-Body Image Stabilization (IBIS) found in Sony Alpha camera bodies.
The DC motor is audible during autofocus. For professional video work, manual focus or using an external microphone is recommended to avoid picking up motor noise.