Zorua, VVV's probability is figured out by law of diminishing probabilities. You can look for it in the Sharpedo section of my Cities article, although I basically just copied and pasted Zero's explanation of it lol.
Zorua, Definitely. Make sure to have some questions to ask this time! And, like CMP said, mods are available at all times for questions on Skype or chat, so don't wait for certain days to address a problem or ask a question. :3