Still getting the same errors. I'll check my installer then and report back soon.
EDIT: I've checked the build version and it's 14D136. The correct kernel is also in the directory you've mentioned. I've made an installer using Yosemite 10.10.1 last week, which managed to install but later on couldn't boot. Since Yosemite isn't very stable in VirtualBox, I've decided to attempt to make another (this) installer in more-stable Mavericks. Do you reckon there's a difference between making an installer in Mavericks and Yosemite?