I have one of these processors myself and have had no compatibility problems with the RTM version of Windows 8. I did have some overhead issues on earlier versions but it would seem Intel has been in communication with the Win8 dev team since Release Preview.
I do know RST is fully supported on Win8. Simply install the Win7 drivers until intel releases an "official" win8 version.
I do not know about rapid start since Windows 8 has its own method for trimming start times. What I do know is that I currently have Rapid Start enabled on the motherboard and my current boot times from cold off to login screen is about 20 seconds, 12 of which are loading my two raid controllers. NOTE: I am booting into an SSD so your mileage may vary.