Piano Songs Database

We are building a piano songs database for a mobile app. The database will be dynamic and new songs will be added over time. The app will display what keys the players will have to press to play the songs, in a similar fashion to Synthesia. First we are going to build the data entry site where piano songs can be entered in the easiest way possible. We will need your advice on how the entry should be structured to make is as easy as possible. We will also need your advice on what format to use, piano sheet music, piano tabs, etc. After the data entry site is complete we are going to need someone to submit new songs and categories on an ongoing basis. We would like to reach around 1,000 songs within one year. The ability to find high quality piano sound fonts will be also appreciated.