The island speaks to Ben. Maybe Jacob noticed some things Ben was told to do wasn’t from him and figured out MIB’s plan and told Ben to bring whoever fit the description that would fit a loophole.

We do not know who placed the ‘circle of ash’ around Jacob’s cabin or why. However, I think we can determine it was to keep Jacob’s friend trapped inside.

I re-watched Cabin Fever and noted that Locke carefully stepped over the ash, so I am not sure who broke it, and/or when. But, Ben may have broken it.

I am in the camp, who believes that the Smoke Monster is a separate entity at this point. The Smoke Monster did appear as Walt to Locke when he was in the pit.

My understanding of this was, that it was ‘the island’ who was telling Locke he had more work to do.

As for Jacob’s friend finding his loophole, I think that the long-term animosity between Ben & Locke provided him with all of the ammunition that was needed to succeed with his plan. Both Ben & Locke were pawns, but I believe Ben was the bigger pawn of the two!

Nice theory!