I suggest you doing 1 and 2.
You can use the cord that came with the nook to move any public domain books onto the Nook (they will move to the "My Documents" section). I have to agree with the not using the library option though. The books might expire before she opens the gift, and I know some people have to get a handle on using the library lending function anyway.
As to getting her books or stuff she can start reading day of: get a gift gard. All she will have to do is put the card on her B&N account when she registers the Nook and she can start getting books immediately. Pick it out on the site, purchase and download. It takes ~10 seconds to download a purchased book, so she'll be reading in no time.