XX:ParallelGCThreads will not enable a MC server to use multiple threads. Most of the "commonly" recommended java options serve no purpose any longer in a 6+ environment.
As far as the build goes, that Xeon is overkill.. Since you're running the server at home desktop components will suit you fine. If you're looking for inexpensive virtualization I'd recommend an ESXi WhiteBox like my ESX220 build (you can cut back on the cores if needed). Minecraft benefits most from core speed not a large number of cores so apply your budget accordingly. There is nothing like the flexibility virtualization affords you. Oh and go Ramdisk.
ESXi + Debian + Minecraft + Ramdisk =