Any charge for free app and issues at Apple Store?

In case we need to create free issues or even apps for iPad (from a non-profit organization), what will the incurred costs be through the whole process?

i.e. From the time of development of issues and the app in which the issues may work - is there any registration or license fees involved, till it reaches all customers - provided the package is for free?

Any charge for free app and issues at Apple Store for iOS apps for iPad?