Doors to the ceremony venue will open at 3:30pm and everyone has to be seated by 3:45pm when the ceremony starts so I would suggest showing up a little sooner than that so you have time to find the venue and park even if you have to wait a few minutes before going in.
Yes, both venues have a parking lot dedicated to the spaces.
While we do love everyone's children, we have decided to make this an adult only celebration with the exception of our sibling's children.