Sorry, I haven't had time to read the entire thread, but a few thoughts. Practice, practice, practice. Whether it's parking lot, early in the morning when there is no traffic, etc... the more seat time she gets, the better.
Private lessons aren't a bad idea, ever.
If you're going to teach her yourself, one tip I always give is to preach being smooth. I've taught a lot of people to drive over the years, and one thing I find with anyone struggling to master it is they tend to hack at the wheel, stab at the pedals. Inputs should be smooth and progressive. Don't "fight" the wheel and pedals, work with them. It's a dance.
Another idea...seriously...is to do something called autocross (autox). If you're not familiar with it, it's the most basic form of "racing" you can get. It's where cones are set up in a giant parking lot and cars go one at a time to go through the cones as fast as you can. The events are well organized and sanctioned, so they're perfectly legal and safe. Before I got into wheel to wheel racing, I did a ton of autox. We would see some teens learning to drive show up. It sure teaches you how to be smooth, car control, looking ahead and many other tools you can use for safe driving on the street.