I think St. Agnus (catholic) has a preschool adjacent, its downtown and is also close to springfield ballet on walmut street and the downtown YMCA (I am pretty sure southside catholic schools have huge waitlists so you would have to send your kids to a downtown/midtown school like St. Joe or St. Agnus)
Also Battlefield is the best southside town, it is connected to springfield with a four lane highway and there is never any traffic on it. Battlefield would also be convienent for new covenant acadamy on kansas expressway.
you will regret moving to nixa if you have to drive US160/Cambell during rush hour.
I also wouldn't recommend looking between springfield and ozark or rogersville along US60 or US65 for the next few years since you would have a big headache of deaing with years of construction after the 60/65 reconstruction begins next year.
US 60/65 Interchange -construction website