At this point I would wipe out the raid config and try to install the OS on a single sata but yes you will later have to format and reinstall to set up the raid but this way we will see if the OS will install and if everthing is stable, if and when the OS installes. This will eliminate a lot of steps and help us to tell if its hardware related or a bad config in bios or with the raid setup or drivers.
I Ain't no expert with raid but the few systems I did setup I pretty much did what you described and luckly it worked. I know when either trying to install a raid array or even a single sata and I choose the wrong driver the system would just sit there and not move on to the next screen, it would never reboot so I am thinking there is some hardware that is causing the problem that we can more easily track down by doing a single drive install.
I am going to be away for the weekend so I will ask for additional staff help, maybe someone with more experiance with raid can give us some pointers.
Keep us posted on how the single sata install works and if the OS would install if everthing is stable.