From 11:00PM PDT on Friday, July 1 until 5:00AM PDT on Saturday, July 2, the Shmoop engineering elves will be making tweaks and improvements to the site. That means Shmoop will be unavailable for use during that time. Thanks for your patience!
Jackson is the second-in-command of Squad 451. She's supposed to take over if anything happens to Boggs. It's debatable, originally, whether she trusts Katniss or not. By the end of the book, we see that she did; Jackson sacrifices herself to save Katniss and the others when they're moving through the underground tunnels.