Go to myers and register for a wedding list. You can actually instruct myers to advise a voucher is appreciated to go towards "x, y & z" and then just let people know there's a registry at myers.

For the kids, I'd be tempted to say something like "We want you to enjoy our day as much as we plan to. We don't want you to be worrying about unfenced pool area, and suggest children stay safe at home" maybe?