Don't buy servers from a company for this. They charge an astronomical amount for the brand name and warranty. Building this yourself will provide a warranty on each piece and at a lower cost. As for processors, go with the fastest chip you can find on the 1150 socket. That would be the 4770K but the 4670K is almost the same for $100 cheaper. As for internet speeds, 100mbps should be enough. I would say anything above 50mbps would be enough but 100mbps is better. As for suggestions, the solid state drive was one of them. Its stupidly fast but could be overkill depending on your needs. You should make your backups to a different drive though, 30 people playing and generating new terrain could trash an SSD faster than a normal home user would.