We'll have 2 null objects in the scene that will define the corners of a box. Just like the clicks in creating a rectangle with the marquee tool, the first null defines the origin, and the other is the direction the box goes in. Take this as an exercise in understanding how expressions work with different properties, and hey, you could learn something useful.
And it's awesome! Adobe are hard at work making their CC applications the best they can be and are probably gunning for the high-end industry, but they still have some ways to go.
At NAB, Adobe announced a new update coming, and uploaded a bunch of videos to their channel demonstrating the new features, including this nice summary:
I'm particularly impressed by the new Character animation tools and the live playback in AE. Face-tracking is also cool, but I probably won't use that very often, much like the mobile applications. Color Tools in Premiere was a long over-due update, although they have the dedicated grading application, SpeedGrade, this makes things a little easier for editors.
Media Encoder is rapidly growing into a powerful standalone application that's reduced my uses of AE's Render Queue. Almost everything I do comes out of Media Encoder.
Let's take a closer look at some interesting new features: