1. From birth pretty much.
2. Probably, but I have no idea what normal looks like, DS is an only.
3. Still working on that one, but testing helped a lot.

Just have fun with your DD and enjoy the toddler/preschool years. If I could I would go back and give myself that very advice. 18mo-2yrs was my favorite time with DS and I wish I had known to appreciate it more. And take lots of pictures, she's likely cuter right now than she will ever be again in her life :p