Find a way to make the drive fun for her. Set up some rituals that a kid would look forward to along the way. Favorite place to eat/ buy her something. It's borderline bribery, but better than risking an early burnout caused by car rides. As for stance and width, at her age and ability minor adjustments won't yield mind blowing results. Ask her and make sure she's comfortable, past that...just let her progress and have fun. Once she starts feeling the flow of the board, she'll want to learn and progress on her own ambition.
Either way this is super inspirational. As the father of a 2 year old boy, I've got big dreams of shredding. I'll never force him, but I'd love to go and hit the slopes with him. Keep having fun!
If you want to be a chick, a dude, a tent, or a velociraptor be my guest, but if you choose the last one you bet your ass I will have a spaz-12 to your face.