Hi,
Yes, side by side 3D was removed for Capture 2018 as such screens are no longer in production and the technology has been abandoned.
Clamp to sRGB means that no colours outside the sRGB gamut are produced. This is essentially in effect when you rendering images or movies since Capture only produces sRGB images/movies. On screen however, given that you screen supports it, Capture can produce more saturated colours.