I'm appropriately ashamed of having to ask, seeing as I took/stalked the MWPP classroom for quite a while. >.>

I'm currently working on a one-shot about Petunia and I don't want to throw in any lines about Lily that might not be appropriate to the year. Petunia is ten at the time.

When did Severus begin watching Lily (is it said, or is there a general age that's implied)?
When did Severus approach Lily for the first time? [ages]
Is there/how much of an age difference is there between Lily and Petunia?
Is anything ever said about the Evans girl's parents?

Of all the times I've reread the books, DH is the only one that I've read only once. >.<