Hello Renzo,
The 183 days per year do not need to be continuous; you can leave every two months if needed.
In response to your second question, note that you will be able to apply for their nationality ( of they live abroad) once you are already a Spanish national, via the Option route, if by then they are under 20 years old. Your wife cannot be included. She need to reside in Spain first and meet the requirements.
Regards,
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