Welcome back! I want to get involved in this when I get back to the states. I can help with the eink I/O. Or you can borrow some of JoppyFur's code.
Also, check out the recent progress on hawhill's Advanced Toolkit thread. At this point, the K3 USB Downloader mode "debricking" process is a lot more advanced than K4/K5 debricking (which has not seen progress since it was posted, because it worked okay and we have other things to do).
Looking forward to that "One Button Click" debricking you promised us in your post that provided the first push to get the "fastboot manifesto / select boot / simple debricking" series of threads going. I *wanted* to go further than just pushing custom uboots to it, but like you, I have other interests and other time-demanding things in my life.
Glad to see you back, and looking forward to more great things from you!.
P.S. To see what we can do with eink animation, check out the "geekmaster kindle video player" thread and watch some videos.