Do I still need a reservation even if I’m not using their designated picnic area for a bday bbq? (No bounce house, just chairs and tables)

No you dont need a reservation just need to get a spot and set up that goes the same at any park reservations are for when you have a jump house or use the covered areas

No

No, then it would be more first come first serve. You just need to find and set up your non-designated area first.