Welcome ot the Community,
I don't know if there's some simple documentation for disk usage. However, it's actually very easy. What you basically do is to keep ~20% free disk space on a datastore (e.g. for snapshots) and ensure you monitor disk usage in case you use Thin Provisioning (which I would not do in this case).
There's no need for a dedicated disk for ESXi. The installation will automatically partition the installation disk. ESXi will only consume ~5GB disk space anyway.
Some hints regarding local storage. Make sure the RAID controller is listed in VMware's HCL (http://www.vmware.com/go/hcl) and has a BBU (battery-backed write cache) attached. This makes a HUGE difference in disk performance. Also make sure you use at least 4 disks for RAID5.
How do you plan for backup? In case you plan to use a VM based backup, you may need to get a paid license for the host (essentials will do) to unlock the API.
André