Can a very small marriage ceremony be held at the park?

Yes you can

Yes, need to speak to park manGer to request a placed

They have pavilions that can be reserved.

Talk to the City's Parks and Recreation Department for helpful information.

Talk to the park; I don't see why not.

I would contact the park for reservations and costs. I think you can reserve certain spots. The Railroad is separate from the park. If you want to reserve any of their space you should contact them directly.

there's a space you can reserve for events, i think its for any occasion.