Re: Child PCs
As was pointed out, by RAW it's not possible to play a character who is not an adult, so there are no stats for child characters. That said, it wouldn't be too hard to just do a linear progression of stats down from the minimum adult age of the race to whatever you think they should be at birth. For example, if all stats are 1 at birth for a human, and adult is at 16, then their stats would need to up by roughly 2 points every 3 years to be at 10 by age 16. Or if you wanted to make it a little simpler, you could just make it that every physical and mental stat is reduced by 1 point for every 2 years you are less than 16, rounded up. So at 15 or 14 you'd have a -1 penalty to every score. At 13 or 12 a -2, and so on.
If build a man a fire, he'll be warm for a day.
If you set a man on fire, he'll be warm for the rest of his life.