If your child was included in the invite then yes. As much as we would love to have everyone's child there, we are only allowed so many people at the venue.
Of course no white. Feel free to wear cocktail to semi formal clothing.
In your invitation it will tell you if you are allowed a plus one.
Guests should arrive between 2:30pm-3:00pm. Ceremony start at 3:00pm, if you are late we ask that you wait until after the ceremony to come into the wedding.