Two ways to know: 1) Check if they are listed on the envelope of your invitation. 2) When you RSVP, invited children will be listed.
Smart Casual: somewhere between formal and casual - what you wear when you can't wear jeans and a t-shirt but you're not in suit/evening gown territory either. (Think - golf course/country club dress code!)
The event is no host/cash bar. If you wish to imbibe, feel free! Check out the food menu here: http://www.darkhorsebrewery.com/new-grub-menu