Hiya!
I live in McKinney... I can help you out with some of what you're looking for!
1. Shopping: Stonebriar Center in Plano is a great place to shop for basic stuff. It's off Preston and 121 in Plano, easy to get to. There is great, more unique shopping in Dallas, but for general stuff it's a great mall. Also there are restaurants and a Target and shoes stores, etc in the shops around the mall, including a Toys R Us and a Learning Express.
2. Traffic: Avoid the 635 construction!!! You'll know it when you see it.
3. Pediatricians. I have a great ped in McKinney, her name is Dr. Catherine Frank... if you search for her she shows up. She is fabulous.
4. OBs... can't help you there as I find all OBs in Dallas fairly evil (think 45% c-section rate) but if you want a midwife I can give you a dozen names.
HTH!