We're planning on taking a trip to Walt Disney World in July (probably the 2nd week). We have a range of ages to accomodate.....dad=42 myself=39 son=18 his girlfriend=18 son=14 and son=6. The kids love amusement parks and waterparks.
That's a decent range. How long are you going and have you been before? Based on what you've said in this one sentence I would suggest that you get tickets with plus options so that you can go to the water parks if you want to (and you may since July can get quite warm) and the 18yo can go to Pleasure Island at night.
The only thing I know I want to see in Florida is the ocean ....as long as I get to see that I'll be happy.
WDW is pretty much smack in the middle of the state. Having just gotten off a
Disney cruise the first beach area that comes to mind is the space coast (port canaveral area). It's a little more than a hour from WDW. You can check the cruise line board for info on beachs/resorts near there as often times people arrive early for a cruise and enjoy the area.
Would we benefit from renting a car while we stay there?
If you are planning on driving to the coast to go to the beach you would most likely definitely save money getting a car versus some kind of car service.
Anyway, where is the most affordable places to stay and eat? I'd like to save as much money as possible.
Disney resort are classified in three categories Value, Moderate and Deluxe. The value resorts would be the most affordable on property. Those resorts are Pop Century and the All Star Resorts (Movies, Music & Sports). I suggest you visit allearnet.com for more information on and pictures of these resorts.
The oldes boys and my husband eat like theirs no tomorrow so where can we get the most for our money.
I think that you'll find that the portions at disney are fine, not real small or anything. Though, maybe you would be interested in checking out some of the all you care to eat buffets. Again, I would suggest you visit allearnet.com for menus and pricing.
Should we buy all our tickets in advance? Where do we buy them?
Depending on your plans, you might benefit from buying a package from Disney which would include your room (or rooms) and tickets (and which be bought in advance). You should decide how many days you foresee yourself spending at the disney parks to detemine how many days worth of tickets you will need. You could also alway wait and buy tickets when you arrive at WDW though they may be slightly more expensive. In case you were wondering (surprise!), ticket information can also be found on allearsnet.com.
If you are looking for a book to get you started I would suggest the Passporter. It would be easy for you to digest quickly in order to enable you to book your trip but at the same time provide enough detail for you to plan the day to day goings-on (parks, attractions, dining options) once you are booked. Don't let the people on here scare you. It is possible to plan a trip on short amount of time (especially since I doubt your group would die if they didn't do Cinderella's Royal Table character breakfast - which normally has to be booked within 2 minutes of them opening reservations for a particular day).
You will find a wealth of information on these boards. It just takes some time to read it all. Feel free to post questions or do a search to see if maybe someone else already posted something like it. Generally people are very friendly and more than happy to help... like me.
....as long as I get to see that I'll be happy. 
