I love the idea, I would help but I am not that experience with modeling and texturing high-quality models and stuff, however that'll hopefully change over the next two semesters as I'm going to be taking video game related classes for college. I'll hopefully be able to start contributing to this fantastic mod instead of just playing it. lol
As for what images and songs to use, maybe show some pictures of Luchador's new weapon models to show how the weapons are being updated again and point out that he's one of the newer members, same with maybe a sample or two of tweaklab? Hopefully showing off some of the new and awesome things from the newer team members will motivate some more people to join.
Maybe show some gameplay comparative footage between some of the old betas to the current game to show how far this mod has come and that it's gotten this far from just GE fans joining and helping to make the mod better?