Ok. An errorfree kernel compilation doesn't mean that it works. The first step is to build the same kernel again with a procedure like you have tried so far, that's also my target.
But until now i can't help you because i didn't check anything of the Yocto build process and the necessary kernel patches but i will also try it in the next days and come back here if i get it running. I'm also using ubilinux so we both have the same interest. But i don't need realtime capabilities on the Linux side because the combination with sketches running on the uC should do this for my needs. What i'm missing in the current version is w1 (onewire), usb-sound, udlfb. It would be easy to connect a simple usb soundcard, a 1w sensor or an udl monitor to Edison. I guess 1w will need a small patch for port access.
Maybe there's another guy having a similar idea for building the kernel?
