Island Exits

Viewers are aware of at least two ways to leave the island to return to the mainland:

1. By calculating coordinates according to a formula, it is possible to sail off the island and reach the mainland. Without the coordinates, one always returns to the island. The Others use this method quite often.
2. Turning the Donkey Wheel below the Orchid. Doing so transports the operator to a spot in the desert in Tunisia. It appears that the year of one's return is impossible to predict and uncontrollable.

Is there another island exit viewers have not seen? We are led to ask the question due to the following:

1. How does Jacob leave the island? Notice that so far, it is possible to show that he only visits the island in the present, even though it may appear that he time travels into the past. Sailing from the island would allow him to do so.
2. How did Daniel Faraday leave the island shortly after TT to 1974? Was he even aware of the Donkey Wheel at that time?
   

Perhaps the largest conundrum is posed by Daniel's jump, since he travels back in time to the mainland, and then returns again via DI submarine in 1977, clearly armed with a mission from the information he gained while away. He must have been working for the DI at least some of the time he was gone, since he has photographs from the island and is in their employ.