Simple App Modifications

I have an existing app with source code, build in Cordova, Ionic, Angular, Node.js and MongoDB. The app is Myeventapp, buyed from codecanyon, for android and iOS For this app i need some modifications like: 1) In the first page of app I need a calendar with all events (like attachment) 2) I need a push before 3 days of each event and before 3 hours of each event 3) I need a tab in admin panel for custom notification (ex. if I need to send a custom message to all people) 4) Inside each event I need a button that open the mail client with the subject compiled with name of event and with message compiled ex. From (owner mail) to (myemail) Subject: Event xyz Message: yes I can do it 5) I need the installation of admin panel on my web hosting