System = the android OS and stock appsRegarding the memory, if you into system /storage is shows an inaccurate reading on available memory if you flash any rom not in the stock slot. It's been shown several times in the beans thread.
If you go into a file Explorer, it shows correctly.
Now far as setting the data and system partition. What does each represent? And yes, I'd like to max it out as if this was a regular recovery and treat it like that. I'll flash the same rom clean on every update. Don't care about dual booting different roms.
Data = all app you want to install on the phone from google Play
cache = This is the partition where Android stores frequently accessed data and app components
what does it matter that the memory doesnt read right there if it doesnt hurt anything?