omega44-xt
Gear up ...
Do you remember that almost a decade ago people were installing OS from discs & those were booted from a CD/DVD? Even a portable version of some Linux OS used to run from discs, so definitely you can boot from the disc drive.You cannot.
The caddy replaces the CD drive of a laptop with a SSD/HDD. BUT the SSD/HDD will be detected only by an Operating System and not by the BIOS.