According to the best practices, you will have to get 1TB SSD space for L2 caching. 10xSAS are already quite fast (moreover in RAID0) and I would say it is not necessary right now but might be considered later when you will need to quickly boost your existing performance.
In the case of 3 node configuration, you can surely go with RAID0. You will get an incredible storage performance while redundancy is granted by having 3 mirrored copies of your data provided by StarWind.
StarWind Virtual SAN Free can be installed only on the physical machine running Windows OS (2012 R2 is highly recommended). So if you plan to go with dedicated setup, you should be fine. In the case of CentOS, you can try to run StarWind inside a VM. Obviously, you will need KVM in order to do this ...