We grab breakfast to go from La Brea. They have insanely big croissant breakfast sandwiches that come with a side of potatoes...more than enough for two to share. One of us stops there and the other gets in line for rope drop. Then we eat in line until the park opens. You can also get coffees, pastries, yougurt, etc there.
For Plaza Inn I like the last breakfast reservation (like around 10:30). Then I can still rope drop and knock out a decent selection of rides before breakfast.
Definitely do the WOC dessert party. I would do a later bigger lunch and then you might not even want dinner after the desserts (you also get grapes, bread and cheese). If you do want to eat after, grab something in DTD.
What airline are you flying? They probably have an app so you can just show them your electronic boarding pass. No need to print a paper one. I'd also recommend Uber over the DLE to get to the airport.