Are children allowed in sky clubs?

Guests Members with an Executive membership may access Delta Sky Club with up to 2 guests or immediate family (spouse or domestic partner and children under 21 years of age) complimentary, provided that Delta determines that adequate space exists. Executive Members may bring up to two additional guests for $29 per guest per Club visit. Member must remain with the guests at all times during the visit. Members with an Individual Membership may access Delta Sky Club with up to 2 guests or immediate family (spouse or domestic partner and children under 21 years of age) for $29 per guest per club visit provided that Delta determines that adequate space exists. Member must remain with the guests at all times during the visit. Guest and family privileges apply only when the visitors accompany the member. Guests and family members must abide by Delta Sky Club House Rules. At partner lounges, guest access is subject to the policies of each lounge partner. Delta Sky Club cannot guarantee gu

Yes they are, but the environment is not really amenable to spreading out like some parents like to do for toddlers.

Yes

Yes they are allowed but you may need to pay an additional fee to bring them in depending on your membership type.