The producers in the podcast last week stated that they felt that ABC was over emphasizing the 3 mysteries promotion. I would say that the 3 were:

1. How Jack got his Tatoo, the significance, and translation.
2. Karl reveals that they live on the main island, and only work on projects on the smaller ones.
3. Passengers who were taken (cindy & kids) are not harmed and seemingly content.

My own two personal revelations: 1) Ethan was a surgeon 2)the others do not know about the Brady Bunch

The tatoo will probably be a very relevant detail down the road. We have been told that the character names are important and I think the tatoo is going to be in the same vein. Jack has never felt as though he belonged, and he fights against being the natural leader that people see in him. He possibly has been fighting what will become his destiny his entire life.