As above and is it only active in sport mode?

The Skoda Octavia 4x4 has an Haldex 5th generation system.

The 'clever' LSD on the 230 models is often referred to as an 'half-haldex' only for the front wheels.

If you read on Haldex 5th hän, I guess you will find the answers you are looking for :)

Also, and since it seems it is a torque based system, I assume it should be always active, but no doubt someone else can come and confirm.

No lsd fitted to 4x4.

The haldex is a centre diff.

vRS 4x4 has a XDS+ system, not a mechanical LSD.

 

From www.golfmk7.com :

"Main difference between XDS and XDS+ is, that XDS only actuates the

inner front wheel, while XDS+ also brakes the inner rear wheel (probably
to a lesser degree).
Both XDS and XDS+ do nothing straightline. XDS is uses dynamic relevant 
data like steering angle, lateral acceleration and other data to predict slip 
and understeer, acting even before these occur."