The tunnels

in the He's our leader episode we are introduced to the tunnels. I believe these tunnels lead to the frozen donkey wheel. ben already knew how to move the island which means he knew how to access the wheel through the tunnels. when ben blew up the vault it was to prevent locke from using it. ben probably was using the vault to send himself back and forth through time. you could effectively tell yourself useful information like planes crashing on the island. ben was very familiar with all stations on the island because he was the janitor. he had access to everything.
probably a part of the circle of trust because he has known horace his entire life. after the purge, widmore was exiled and ben either used a polar bear to move the island or he did it himself. he did say he was a perfered customer at the hotel in tunisa. plus i have always thought that chang is the one who used a polar bear to test what happens when the wheel is turn. he drugs a bear then leaves the bear in the chamber to turn the wheel. anyway i think there is more storyline for the tunnels to come.

I think there is something to your take on the polar bear training. Like those tests in the cages where Sawyer and kate were held on hydra island. Maybe they made a training donkey wheel to teach the bear how to turn the wheel, then put him in the chamber to do it for real.

I think Jacob brought Egyptians to the island first and they built all that including the statue. They seemed to have lived peacefully for a long while but obviously the infighting started (or more people were brought you started a fight) and the statue was destroyed.