Windows 10 Dual boot 10 with 8.1 separate drive

[RIck51]

Hi I have installed Windows 8.1 on a separate drive. Windows 10 already installed on mt Dell desktop
I have two questions :
1. Does or should I disable fast boot and secure boot in Bios?
2. I am using easy bcd to set up the dual boot option screen. Which bootloader should I use as default 10 or 8
1?
Any and all advise appreciated