Finish Ionic app

I have an ionic app almost ready. What is still missing there: 1. we have cards there and the effect currently used is not nice. so I want it to look like this: [login to view URL] 2. currently the way it is is that when entering the section it loads all data at once. since it contains lots of images and sounds it takes about 30 seconds. What I want is that it does some sort of lazy loading - first loads data for 30 items, then if the user scrolls down another 30, etc. And when user enters card detail page it will load all the remaining cards data in the background also it should cache everything, however it should also check in the api if the date of update of each section is newever than the version of data in app. if it is newever it should clean cache for this section and load all data again to cache 3. the transitions between screens are somehow slow. so we need to make it smoother 4. connect existing UI of contact form to API (send form data to existing api) 5. properly test the app on different devices including ios