You and your family will have an incredible time!! This board is a great place for tips/ideas/strategies. I'm not a DisPro like some of these folks, but I have been a few times and learned what I like to do. Have you never been? or, just not with your family?
I over-plan for months before the trip. which park on which day? Which ride first, second, last? Parade schedule? restaurants I want to try? What time do I want to get up? leave the park? any rides to skip? I try to think about everything, and read as much as possible. Then, when I get there, I just go with the flow. I think, however, that it flows much better and faster if I have a plan before I arrive. I have some Disney friends who have no real plan, other than which park to go to on which day. It works for them, but, I can't do it.
My daughter is nearly 4. We went when she was nearly 2, and had a much better/easier time than I imagined. We arrived for park opening/rope drop every day, and left by 4:00 or so, with no return to the hotel. A lot of people strongly recommend the midday break. We were staying at AllStar Movies, and it was just too far and too much hassle to get there and back. We planned for short days in the park, and everyone was happy.
I subscribed to touringplans.com, and have read The Unofficial Guide cover to cover. Tons of good info. I am basing schedule for my upcoming trip on the Crowd Calendar on touringplans. I have no idea if it's accurate or not, but I decided to go with it. We'll see.
I'm a fan of the dining plans, although they are definitely not a bargain. It's just easier, to me, for budgeting purposes. I like knowing that I have a number of meals for the trip, rather than a max $$ per day. I would go over budget every single day.
I buy little Disney toys and glow necklaces before we go. Saves a lot of money.
My daughter LOVES LOVES LOVES the characters and parades. Make sure you get a couple of character meals in there. Check the parade schedule in the morning (it's also on touringplans.com). She really liked that more than the rides (of course, she was 2).
Photopass. I can't say enough about the photopass system. Yes, it's expensive if you order individual pictures. But, you can get the whole CD of all of them for $120. And, you don't have to fool with taking the pictures. AND, you get to be in the pictures with your family.
It's so wonderful for all of you that you are taking this trip. A ton of memories to cherish!! God bless your sweet little one, and the big kids for being so awesome! Have fun!!
Congrats on your upcoming trip! Your family will have a wonderful time. 
