If your invitation says "And Guest", then yes, otherwise we'd prefer it was just you.
It's an afternoon summery wedding in the park, so think less evening gown and more nice summer date attire. We'll be in the grass for part of it, and weather is hard to predict at the beginning of September (hot? cool?) so keep that in mind!
If they're included in the invitation (if we know and love them and they know and love us!) then yes, otherwise, please come just you!
Unfortunately, the parking lot is public and may be used by other park visitors. If you are able, please save any empty spaces for those who may have trouble walking across the park. There are smaller streets throughout the park with curbside parking. Carpooling may be a good idea! Make sure to plan for extra time.