IONIC CORDOVA FIREBASE ANDROID & IOS APP CODE MODIFICATIONS AND UPLOAD

We are a Web Agency which builds websites & APP for clients around the globe. A large chuck of our clients are in Africa and are low budget Solo Entrepreneurs , small businesses and African charity based organizations [login to view URL] We want to hire an expert IONIC developer who can change code very easily for android APP upgrade and make changes in screens coding to make compatible for IOS. He will work on MAC OS on XCODE to modify an existing APP already launched on google play store but now require some modifications and required to upload also to APPLE STORE. The Android app need to be function as it should and so the following modifications must be made to the APP; 1. The app should be made to load faster and load from back-end. The picture and text should load from back end, generally reduce task done on main thread and push most task to the background. 2. The default background thumbnail should be replaced with project logo/replaced completely with actual picture from back-end 3. The Bible in the app should load from back-end not from a link and should display correctly for users 3. Change screenshots in Google Play Store 4. Splash screen residing and redesigning 5. Fix audio mp3 playing problems. 6. Hymns to load from back end and all texts. 7. Make app content available in offline mode at least texts and pictures. 8. Secure Database In the console 9. Correct or update codes for iOS version and upload to Apple Store 10. Advice of better operations of the APP. This job is for someone who is an expert IONIC developer and has completed APPs using IONIC.