Debbie, the answer to both of your questions is YES!
If you are wanting to dine at any of the table service restaurants then you are highly recommended to make advance reservations for that meal. These dining establishments are extremely popular and because of the number of guests to the parks it would be highly unlikely that you could walk up and get a table at a time that is desirable. (for our family dining at 9 or 9:30 at night is not a good situation)
I suggest you make a basic plan for your stay and decide what park on what day and coordinate a dining reservation for each. You can do that 90 days out from your arrival date by calling 407-939-3463. The Disney website has all the restaurants listed by park and resort,
www.disneyworld.com .
There are numerous quick serve or counter serve restaurants as well through-out Walt Disney World. You do
not need a reservation for these locations and many have tables in that area for you to dine at. Again review the choices on the website and if you want to check out specific menus you can find the most recent at
www.allears.net (type menus in the search box).
Consider making a few reservations...perhaps your boys would like to dine with characters one time during your stay. You can cancel later but it will become increasingly more difficult to obtain them the closer you get to your vacation time.