That's true about not paying for admission. You may not even have to pay to park, if you park on one of the surrounding streets. VA Rt.60(Richmond Rd) is a good bet for free parking. Walk past the William & Mary Campus, cross the street (carefully) the point where the W&M Campus meets Colonial Williamsburg is in the shape of a "V"-called "confusion corner" because of the potential accidents there, walk one block thru Merchant's Square (shopping), and you're there.
Kids being Kids, walk the around the town and see if they're interested before you put your money down. You can walk up/down all the streets. The Building Attractions have Union Jack flags in front of them and you can't go in without an admission badge, but that's it.
If, after checking the place out, you decide to purchase passes, you can do so at a little building called the Lumber House, on the Duke of Gloucester St. (the main street). No need to move your car, if you left it on the street.
You may want to consider driving the Colonial Parkway. It's a very nice drive, kind of like the Canadian side of the Niagara River. It runs from Jamestown (admission) to Yorktown. Yorktown like Williamsburg is free to walk around, I think the Battlefield is free and the little town of Yorktown on the York River is free but full of over priced tourist items.
There's a huge Outlet Mall on Rt 60 (Richmond Rd). VA Rt. 5 has several Plantations between I-295 & Williamsburg.
If you go to Busch Gardens stay away on the weekends. Too crowded, long lines, especially for the Roller Coasters.
Enjoy, there's a lot to see and do.