I think it won't work at that frequency, because 522 works at 13,56MHz. This are the compatible cards or tags: mifare1 S50, mifare1 S70 MIFARE Ultralight, mifare Pro, MIFARE DESFire.
That's easy, you only need an arduino connected to the RFID522, and when it detects the legband, maybe with a servo, it opens the feeding (room or how is it?).
In this part I don't understand you, do you want to sort the birds by their color LED (If you want to pair the LED to a bird it needs a battery and I don't know too much of birds, but I don't think it is healthy) and then with maybe a color sensor open an specific feeder? If you want to do that, it's more easy, just write to the legband an ID which the RFID can read, and then depending on the ID you can open an specific feeder.
And what about Cayenne? You will use it for something, perhaps to see if a feeder has been opened?