Install your OS on the Vertex 4. I wouldn't worry about building a cache for your spinner. Just install to the Vertex 4 first and keep the other two out of the system while you get it all installed. Then after you have your drivers loaded and such install the Solid and use it as a scratch drive. Download to it for fast Zip and Rar access. Then put in your spinner and use it for 'nearline' storage, music, movies, large files and such.
What you are doing it creating a tiered storage system. If I get time this month I'll write an article on it. I've wanted to do so for a long time.