We'll definitely be checking for reservations again. There was a breakfast we were going to try to go to with Stitch, but there weren't any times left so we just gave up. And we didn't even attempt to do any of the dinners because we were so late planning it all. We weren't aware that you should actually start planning in advance. It's already been decided that we're coming back in a few years when our daughter is older and we have more children. We'll definitely be planning in advance for that. Plus we plan on staying at a resort.
If you really want reservations to a particular restaurant you should never give up. Last couple of years our trips were kind of last minute deals, but by simply being persistent in checking the reservations on a daily and nightly basis we got all the ones that we wanted.
As someone said make use of character dining to eliminate some of your meet and greets.... That is really key because some of the meet and greets during a busy time will be insanely long.
The one thing I think you are making a mistake at is prepping your daughter for the meet and greets by fixing up special pages for the princesses... If you do that don't let her know that they are available, make sure you prep her with, "just in case we run into XXX" that way you wont have to deal with the disappointment of her not getting all the signatures.... Because the odds are unless you want to spend most of your vacation in line, she wont get all the meet and greets that she will expect.
Also do a google search for a site called kennythepirate, it has a list of characters and where they do meet and greets, that will come in handy if you are really wanting to focus on meet and greets because some of them have lots of places they show up while others will only show up at one place or only during a special event... it will save you from looking in vain for a character that may be exceedingly rare.
As for using an early morning breakfast to get early entry into the park... Yes we have done that with Be Our Guest, but doing it doesn't help with any meet and greet unless you want to go to the one you are looking for and be first in line when the park opens.... In other words you'll still be waiting only at the front of a line.... If you do get an early morning breakfast in the park you are better off using that opportunity for 1)photos without a huge crowd in your photo, about the only way you will ever get a good photo of your kid and castle without a huge crowd of unknown people in the background will be the early breakfast, and 2) to get a quick entry on the seven dwarves mine train.
Oh... One last thing measure your daughter to make sure of her height and then verify she is tall enough for the rides you want to do before you get there, when your son/daughter find out they are too short upon arrival it tends to result in lots of crying... if you know they aren't tall enough for a particular ride you can then not mention it and avoid that problem.