Welcome to the Community - To be able to do vMotion you will need to have two ESXi hosts that have compatible CPUs - If this for production I would confirm whatever server you are looking to buy is on the HCL - http://www.vmware.com/resources/compatibility/search.php - if not you can also look at http://vm-help.com/ or http://ultimatewhitebox.com/ for machines that are not on the official HCL but people have been able to successfully install vSphere
Also be aware that for vmotion you will need to purchase vsphere licenses -
In terms of NICs once again is going to depend on whether this if for production or testing - if it is for production you will want at least 2 NICs for redundancy
I have also moved this thread to the appropriate forum -