SATA converter for DVD drive in laptops?

yes often the latops bios has a boot order selection where you can make it the first boot device, oterhtimes you will need to select the boot device at startup (often its pressing f11 or f12) see the bottom of your screen during your boot up for a message saying pressXX for boot options (or similar)
At worst case, you swap the new caddy drive for the old internal drive (ie - old drive is now in the caddy)