Yes. Daycare is a great way to build up your child's immune system by exposing him to lots of different viruses. All kids get sick, but kids who go to daycare do tend to get more colds. But don't despair, good daycares are also a fun place to play, socialize with other kids, and enjoy toys you don't have at home.
Yes. Children in daycare get nearly twice the frequency of respiratory infections (colds, sinus infections, ear infecctions) as children who are not in daycare. While this can become frustrating, it can help stimulate their immune system and make them less likely to get sick upon entering school at age 6. It may even make them less likely to develop allergies in the long run.
Yes. The more children your baby is exposed to the more often she will get ill. The younger your baby is exposed the more likely they are to get ear infections or lower respiratory tract symptoms.