Hi Tor, first time poster hereNo central lock, it uses a haldex system that only engaged when the front starts to lose traction.
Mine has a rear diff lock but this can only be specced at manufacture and can not be added later.
The abs is used to stop a single front wheel spinning by braking the spinning side to force power to the non spinning wheel.
Because I drive well off the beaten track I fitted a Van Der Veer haldex controller to allow me to manually control the haldex and force 50/50 split. The main issue with the van controlling it is that it's reactive. Waiting for the fronts to lose traction before dumping drive to the rear wheels just didn't cut it for me (I have been rather simplistic with my explanation)
The rear diff lock was an expensive option but it has gotten me out of a couple of places I would otherwise have struggled with.
Hope this helps.