R.C.
Most of my expertise is in Disney World, but I have visited Disneyland and I have done the parks with a young child. My biggest recommendation is stay on your daughter's schedule. Nothing ruins Disney faster than a cranky child! I So eat when she's hungry, leave to have her take a nap (if she still naps).
haven't been there in several years either, but I bet they have a character breakfast with the princesses which is the best place for your daughter to see them. If she already has a princess costume that can add to the fun if she wears it to Disneyland (just be extremely careful of long skirts) or they probably have someplace for her to get "princessed out."
For discounted tickets, I always go to AAA.
I think the older park is a better bet for your daughter, so you're on the right track. I don't remember anything particularly scary there, but I have to admit my kids were a little older. Use FASTPASS if it's available and don't try to see everything. I always try to focus on the experience of Disney rather than trying to go on all the rides.
Since you're daughter is so young, she'll probably only remember flashes like meeting Cinderella, but you'll love seeing Disneyland through her eyes.
Hope there's something in here you can use!