craftgrrl | Sewing Pattern Help & Quilting Question

Q #1. Okay, so I was looking at sewing patterns last night at JoAnns (which, btw, they have simplicity ones on sale 5 for $5, at least here they do) and was reading the back and got all sorts of confused.

I wear a size 4-6, depending on how it is made, but the measurements on the back for the size 6 seemed too small, and none of the measurements added up. Like the waist for a 6 said 23, but I'd have to be anorexic to even fit that and I'm really thin. And if went with the measurement for my waist, then my it looked as though I'm wearing a size 8, but the chest and the other measurement seemed too big.

Am I reading this wrong? What do the weird measurements for sizes mean? I don't have the pattern yet (today is payday, therefore me going out and spending lots of money on patterns!) to see the instructions, but I'm afraid to get something and then it not work.

And Q #2 - I'm making a baby quilt for my sister, who is due in September. I don't know if this quilt will end up more of a decorative thing, or if she'll actually use it, but the way I'm planning on making it is just some jungle/animal blocks and orange blocks on the front, and some light yellow flannel in the back.

Now, here's my actual question. Should I just sew it like that, or should I put the batting in it? This is the first quilt I've made, and I'm afraid that if I put batting in it and she uses it then the baby will get too hot - and at the same time, she'll be having the kid in August/September, which means Winter is on the way, so maybe I should because of that?