You refer to going to a park called Disney World. I just wanted to clarify that there is no ONE park called Disney Word. I think what you are calling Disney World you mean Magic Kingdom.
Disney World has 4 parks. Magic Kingdom, Animal Kingdom, Epcot and Hollywood Studios. They also have 2 water parks, Typhoon Lagoon and Blizzard Beach.
One thing I will suggest since you have never been before and seem to not know much about anything yet is to buy the UNOFFICIAL GUIDE TO DISNEY WITH KIDS 2012. You can order it off Amazon for about $12 and it has tons of valuable info for new Disney guests.
We have stayed on property and off property both. We only stayed ON property because we got a good FREE DINING promotion. If you don't get a really good 30% off room discount or free dining promo it is going to cheaper to stay off property.
You can stay in a value room for around $115 a night but for that kind of money you can go through VRBO or Villa Direct and rent a 3 or 4 bedroom house with a private pool and a game room for $100 a night or less.
You can also stay at the Quality Suites Lake Buena Vista for around $80 a night and it has a living room and a kitchen in it. It is located between Disney and the Universal parks which comes in handy if you plan on going to both.
I would suggest try not to overwhelm yourself. Take in little bits of info in small doses and spend a lot of time reading these boards and asking questions. Check out all the categories on the boards. The Theme Park board, the Budget board, the Community board. There is even boards for resorts and dining. Don't just confine yourself to one board on here.
As someone else suggested, eating at Disney can be expensive but the park quick service food is usually no more expensive than any public venue like a theme park or amusement park any where else. Kids meals at the counter service places are around $6 and adults can get a counter service meal for $7 or $8.
We have 5 in our party too and the problem with that is THIS...you can't stay in a normal 4 person room like others can. SO that limits where you can stay on property. In the value resorts you would have to get TWO regular rooms or a FAMILY SUITE that sleeps 6 and costs between $180 and $230 a night.
The vacation rental home can sleep about 10 and the Quality Suites sleeps 6.
There is a moderate hotel on property called the Port Orleans Riverside you can stay in with 5 ppl and it runs around $180 a night.
You can save a lot of money by renting the vacation rental home and making a trip to the grocery store and buying groceries for the week and eating breakfast and supper back at the house and only eating LUNCH in the parks.
That would require a car. So if you are not driving to WDW you would have to rent a car to stay off property but financially it still makes sense because you can get a rental car for a week for usually less than $200.
We always have a car because I do not like or will not ride the Disney buses. I like to be able to get in my own car and come and go as I please.
There is not a real good way to save money on tickets. If you are a member of AAA you can book your package through them and it will save you a few hundred dollars off what it would cost for you to book it yourself on the Disney website. But if you do that, it is like using a travel agent. The reservation belongs to them, not you. And to make any changes to it you have to go through them.
Here is a link to the WDW special offers page. Bookmark it and keep checking it weekly to see if they have any deals that apply to your travel dates. http://disneyworld.disney.go.com/special-offers/
Here is a link to the Quality Suites Lake Buena Vista. If you join their Choice rewards program (free to join) you get discounted rates on the rooms. http://www.qualityinn.com/hotel-orl...&nchild3=&nadult4=&nchild4=&nadult5=&nchild5=
May I suggest the "Unofficial guide to disney world" (the regular one, more info and also has lots of "with kids" info, same author. Also another good one is passporter books, they are spiral bound and have folders in the back to keep your travel notes, documents, pics, It's a great tool. you can go to the website to see the book at passporter.com
Happy planning!