As long as you're not using a port connected to a third party SATA controller, it isn't going to affect performance what port you use. Just put it on the first port, and regarding the RAID you should be able to set that up later without any problems! As long as all OS installs are using AHCI drive settings, enabling RAID won't affect them. The in the past the issue was IDE drives because enabling RAID forces all drives sharing that SATA controller to AHCI.