Hmm...a shortcut straight to boot.img extraction and build would be great as well as streamlining kitchen a bit more.
Also if you're going to tackle the images and so on it would be flooring if you can make it artist friendly.
I would say use image magick's abilities to make it so that it can convert most image formats (most importantly jpg) to a workable rle format.
I feel most artists know their way around enough to make an image compatible so a dimension check is not necessary initially.
But eventually you could allow people to take baby steps until it is practically noob/technically inept friendly for all to change their boot up screens.
In the meantime I could foresee a lot more artists on board. I'm currently an animation illustration major at SJSU and a lot of my friends would be 100%+ lost on these forums. Were it not for a short mainframe C internship at lockheed, I would be absolutely lost as well. And I definitely don't consider myself a developer anymore.
As for other requests, frankly I just started looking at the partitions, but the above would definitely help
Oops and last edit, (I make so many typos) when I have time I can help test a bit. Right now approaching finals so it's crazy