There are a number of suppliers of FireWire adaptor boards, which usually cost bless than $100. See the notes in the latest H8000FW Manual saying which adaptors are best.
FireWire adaptors are PCI cards, so they do not care about USB or SATA.
The RTAS plugin offers remote control only, it does not pass audio. If you do not have ProTools you don't need it. So, no problem !
Audio to and from the H8000FW is handled by the operating system, and will usually work with any Workstation software. In your case, with a PC, the audio is handled by WDM or ASIO
You will need to read the H8000FW Manual to install drivers and to test the configuration. You will have to refer to the Cakewalk documentation to find out how to communicate with WDM or ASIO.