What do these switches do ?

I’ve never seen a set up like that. Pretty nice for off road. Reminds Me of a Detroit Locker racing rear end, my Dad had. Turning corners, one tire would skip and chirp, Lol. It was pretty cool.

 

No. With all switches off you basically have 3 open differentials. Front, rear and power divider. With everything UNlocked power will travel the path of least resistance and any of the 4 wheel ends that has the least traction will spin. (If all things are equal driving down the road power is essentially divided between all 4 wheel ends but as soon as ANY wheel end losses traction it will spin. You could jack up the right rear and it would spin, set it down and Jack up the front left and it would spin.
Now if you lock the power divider or interaxle both front and rear axles are powered and either the left of right wheel ends will spin on front and rear.
Then if you have lockers it will drive both wheel ends on that axle. Engaging the lockers without first engaging the power divider will do nothing because the power will just flow to the axle with the least traction.

Power will always flow to the area of least resistance until you start locking things up.

My experience right rear tire wears out slightly faster than the rest if not rotated.

 

This is the best visual for how a differential works