I am somewhat surprised that you are doing this voluntarily. Though not a member, I haven't heard much nice stuff about the UA clubs. But, I can answer question 2 for you.

1. Unsure.
2. Generally, A, B, and C are referred to as the concourses, and Jeppesen is just check in and baggage claim. You will definitely have to re-clear security to return to any concourse or gate after going to the Jeppesen terminal.