I'm looking for a Mobile App-I have rough use cases and drawings

I'm looking to develop a mobile app that is preferably for both Android and iOS but Android exclusively will suffice. It will use location settings, the on-phone database and need external database connections. It will need to work online and offline (minimal settings). It will need to send notifications to the phone. It will need to correspond with other instances of the app on other phones to send messages (how can be however is easiest for the time being-email, sms, ect). It should also generate a calendar event. It will need to be able to use Paypal in app for payment (no other payments will be needed so no financial user data will be captured.) NDA will be needed (Not certain if freelancer requires it). I'd like the app to upload photos to the external database I want to keep the physical code on project completion like in a private git repo.