"There's a strange dynamic going on that I'm just not smart enough to figure out. As I move closer to moving out, she becomes friendlier. "
Why is this a strange dynamic???? This is the entirely predictable WAS/LBS dynamic. Try reading up on the distancer/pursuer dynamic. I also made a short post to butterflymom about this recently.
Re W's "impinge on your space" comment, she wants reassurance that she has you wrapped around her finger. Don't give it to her. Just say something really warm and friendle: "Thanks, for the support and respect. It really is exciting to create a new world for myself. Maybe I can have you over sometime to my bad pad to thank you! I can host a mean dinner party, you know."