This lens is a cropped sensor lens, therefore there is a magnification factor associated with this lens relating to a full frame sensor (35mm).

Not that I am aware of. Adapting native SLR lenses to Mirrorless cameras takes advantage of the larger mount flange to sensor distances required to accommodate the SLR mirror. In essence they reposition the lens to the same distance from the sensor as on the SLR. This lens is a Sony E mount which is already mirrorless (with a short mount to sensor distance) and so there is no room to fit an adapter unless it also has a corrective lens to allow it to focus on the sensor, which can be done (see the Matabones focal reducers, which effectively 'open' up the aperture) but I'm not aware of any such adapter that is made to fit mirrorless to mirrorless.

If by wide you mean "fish eye" not it is not. It is not a full frame lens so I decided to sell mine. Need a full frame lens for video

I am not bcoz I use it on my fs700 and it's a fatatic lens and this becomes like 75 mm since the sensor size on my cameraThx

If you want to have them all in focus , you might want to shoot at around f-8 , if you want to focus lets say in the singer and blur the other members of the band then I found it best to be around f-2.5 depending on the distance to the subject

The Sony E 50mm f/1.8 OSS Lens (Black), B&H # SO5018B, uses 49mm filter threads and would accept 49mm neutral density (ND) filters.

Yes in all ways

The main difference would be the camera mount. The sony E mount and sony FE mount. It looks like the a6000 is an amount camera so unless you have an E to FE adapter you would have to go with the sony E 50mm.