To the best of my knowledge, RoM will not support SLI mode, so you're essentially using only one of your two video cards. You may very well have to restrict your in-game video settings to achieve best performance.
You're welcome to send a ticket to Support regarding the Surface Shadow issue. Use the Contact Support link in my sig below to do this. You will have to set up a Support account. Please use the email address that is linked to your forum/game account for this.
As for your space limitation issue, the game requires at least that much free space in order to unpack the compressed files for both the basic installation as well as update patches. If you cannot free up enough space on your RAM drive, you will have to relocate the Temp folder to a larger storage device.