Hi,
Welcome to the VMware Community,
I don't find this server on the compatibility matrix (VMware Compatibility Guide) . Anyway if you still want to go ahead and try it, i would suggest you to put the ESXi on a USB or SD card as it saves you the local HD space. And you can use the space for VM datastore. Also make sure you have hardware raid controller if you buy more HD's if you want to configure RAID.
The space that you need totally depends on the size of the VM's you will host.
