Can you get AAA discount at the gate or must you buy ahead and what is the price for adults and children under10 yrs if this is possible?

No they don't offer AAA member discount.

Admission: Mar.-Oct. $24; $21 (active military with ID); $19 (ages 2-11). Rest of year $16; $14 (active military with ID); free (ages 0-1). Parking: $16. Hours: Daily 9:30-5, Mar.-Oct.; 9:30-4, rest of year. Phone for special activity schedules. Closed Jan. 1, Thanksgiving, Christmas Eve, Christmas and Dec. 31. I found this in the AAA website... Hope it helps 😀

Not sure, check the website