Sorry, I'm not sure I understand the question. The properties are pretty self explanatory. What info are you looking for specifically?
Custom 1 (and 2, 3, 4) are registry settings that can be set via frminst.exe command line options or by writing the appropriate registry keys. The original documentation for setting these fields with the 4.5 agent was incorrect and is addressed in KB67385. This only works for ePO 4.5 and Agent 4.5.
Basically you run this command with one or up to all four of the custom field switches:
FrmInst.exe /CustomProps1="Property 1"/CustomProps2="Property 2" /CustomProps3="Property 3" /CustomProps4="Property 4"
The following registry key and values are created:
HKEY_LOCAL_MACHINE\SOFTWARE\Network Associates\ePolicy Orchestrator\Agent\CustomProps\CustomProps1="Property 1"
You can replace "Property #" with any text and use that to create reports / tags / etc like other system properties in ePO.
Total Disk Space is the total of all drives in a system, so if you have a C and D partitions (or physical disks) this property will reflect the sum total of all disks and partitions.
Free Disk Space is the total available space of all drives in a system.
Total System Drive Space is the total disk space of the partition with the OS installation (and would not include additional drives or partitions).
Free System Drive Space is the total available space of the OS partition. This is usefull if you are installing McAfee product on the OS partition since if there is no disk space on the system drive you will not be able to deploy new products, upgrades, patches, DATs, engines, etc.