automatic sms sender android app

I want an application to be developed which will serve the following purposes: Import contact information from Excel file, contact details like - Name, Phone Number, Date of Birth After the contacts are imported from excel file, it should automatically send Birthday Greetings sms to all the contacts on their respective birth dates. Birthday greeting message should be easily editable by the users. App should be flexible. For instance, if the user wants to import the same excel file but with some new contacts in that, all of the contacts should be imported properly. There should be no duplicate entries in the application database. Also user should be allowed to schedule sms by themselves. Users should be able to select Date, Time and enter the message to be sent. Then that message should be sent on the user selected date and time. Attractive UI is must for the app. App should work smoothly on all devices whether low-end or high-end devices. App should be compatible with those devices which don't have any hardware buttons on them, for e.g Nexus.