sorry i'm not good for answering kernel panic issue..
If I got that issue, then i reboot the pc. I always use to boot with usb-hdd (usb bootloader) before the OS X can boot normaly from HDD
I think the problem are:
- BIOS setting (UEFI or EFI BIOS) you must google them to set up for different BIOS configuration of yours
- Bootloader costume for your system, I always uncheck GraphicsEnabler=No (coz my graphics card is ATI) then check Chameleon EFI not Chameleon Standard at Customize screen.
- I've got no clue for installing Yosemite on External IDE HDD. Sorry can't help...
According to your photo, I thinks you mus try to customize bootloader using Multibeast or Clover Configuration tool.