Write an Android application

I need a developer who can modify an already developed android app (Islamic prayer notification application) with the core features as follows: 1) Text and count-down timer (remaining time) notifications of Azan and Iqama timings. 2) Display text and image contents at specific intervals, in header, footer and main screen. 3) The back-end admin panel is managed by an administrator who sets-up Organisations and their access to users. 4) All the notification and content settings are set at organisation level and at every change, pushed to registered devices. 5) Screen sizes required: 15" and 32" Please describe technical details, time required and cost estimates