Installation

A friend is giving me a USB stick with high sierra for me to install tomorrow, i have the following questions:

• Should I unplug every drive except the one i'll install the OS on?
• Already have rEFInd in a drive, will it be able to stay as my main boot loader and add mac into it?
• What do i need to configure with an Asus Prime Z370-P and a GTX 1080?

Thanks