Cordova IONIC Android & iOS APP upgrade & upload

I want to hire expert IONIC developer who can change code very easily. He will work on MAC OS on XCODE to modify and existing Church APP bought on Themeforest, 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