Flowerpower, you wrote:"We know he (Rocker) competes for the reward because in these two pictures we see that John is missing from the group shot of the tribes, and so is Jeremy....can Jeremy compete against John, compete 2 weeks in a row, and not go against his loved one?"
No, Rocker can not compete against Jeremy
In Dalton Ross' video interview with Jeff here:
http://insidetv.ew.com/2014/09/03/survivor-san-juan-del-sur-jeff-probst-redemption-island-exile-island/
Dalton asks what happens if a loved one is voted out and Jeff confirms that the other person would then not be eligible for the Hero Arena challenge.
This challenge "Parallel Universe" was shown in the TVGN preview with the media running the challenge in tag teams. Dalton Ross vs Paravti in stage 1 where you have to balance a ball on a wood disc as you negotiate the obstacle course.
So I believe Julie beats John in this challenge and Julie picks Jeremy to go to Exile Island with John.