I completely agree with you statement about Locke becoming more of a leader than Ben. However we need to understand the whole deal with Jacob and Ben, also how dangerous Locke is to the whole situation.
I believe Locke is of great importance to the island and some kind of prophecy maybe, is he related to the staue with 4 toes we saw earlier in season 2, is the statue of Locke?
I think Jacob has something to do with the original inhabitants of the island i.e. the first leader or god of their world/island and a subserviant inwaiting to the head of all the islands.
Yes I think that there are more islands, we know that where the others are and where our losties are is one island although a big one.
You have to ask yourself why is the rescue bout that the parachute lady has waiting is 80 miles away? that is a long way from the island to be if that is the only island around hey? im guessing that it is out there because that's where the most central point is between all of the islands, therefore you are looking at an area of around 160 miles?