Raspberry Pi Media Player

I need a program on a raspberry pi that will do the following (in these steps)

1. Read the GPIO inputs on the PI (all of the GPIO as inputs), and will display the GPIO number in the console

2. Once step 1 is complete, then the next step is to read a 4 digit number and display it on a 4 digit number readout through the serial port

3. Once step 2 is complete, then we will link the 4 digit number to a MP3 file on a USB or Network attached hard drive directory and play the media through the audio output.

4. Once step 3 is complete, then we need to be able to make a queue of files. Meaning if you enter a 4 digit number, then it will play the file. If you enter another 4 digit number, then it will put that next file in queue. You can put as many files in the queue as you want. Entering 0000 will clear all items in the queue.

If you enter a 4 digit number that does not match a file, then it will just blink the number a couple of times then go back to blank. It should show the 4 digit number of the file it is currently playing unless you are entering a new file number. If you don't complete a number entry after 10 seconds, it should clear the entry.

The application should load automatcially when the pi loads.