With a hypervisor you can assign physical cores to virtual machines so no matter what you do on one host their activity doesn't influence the other. Your game servers would run off their own OS instance and can be setup with a Static IP. Accessing them for file sharing (SMB/NFS/SSH/SFTP/etc) would be doable assuming you set it up on the VM side. You may have to create your own network bridge before you do that though.
No, since you have the 8 pin connector, if your only had the 4 pin then you would run into issues. Not sure how it will affect overclocking, maybe someone else will have some input on that.