The stats come from the canon data book so I might not have the clearest answer to some of them. I'll try to update the list to explain the categories 

@Birch: Total ability I assumed to be an overall ability. Higher grades are for more overall skilled genin, with the lower grades for those that are more specialized in one or two categories.
Latent potential: would be anything from 0 to 4.5. It indicates just how blessed people are genetically and their projected ceiling .The ones getting a 5 are the characters starting of at the sage potential level. I imagined there wouldn't be any 5* at the start.
Luck: More of a random stat, I approached it as a mix between good genes and typical good/bad luck. Now that I think about it, we might be better of just removing it.