First, let me congratulate you on buying the RC522.
Since you mentioned the SPI protocol, I'm assuming you already understand this RFID reader and writer is based on the MFRC522 microcontroller, which exchanges data following the SPI protocol and does so by creating a 13.56 MHz electromagnetic field to communicate with the RFID tags. So, if you're buying tags, make sure they operate on the same frequency as well.
And, as far as extending its functionalities go, your experiments are as good as anybody else's. This is because the RFID RC522 can have endless applications and its functionalities or scripts will be very specific according to what it is being used for. The best I can tell you now is that you could use a 16x2 LCD with the raspberry pi to display some information and keep it handy at the same time.
Now, for the set-up of the RFID RC522 with the raspberry pi, you could follow the instructions in the link I'm providing: http://www.instructables.com/id/Raspberry-Pi-3-Model-B-MIFARE-RC522-RFID-Tag-Readi/
You will also find a link to the necessary python codes that you can just install on your pi from GitHub!
And, if I'm not wrong, there might be a little bit of soldering required to ensure a firm connection as none of the RC522s come with header pins already soldered into it. But, soldering header pins are rather an easy thing to do, for just about anybody. So, gear up, open the link I've provided and get started with leveraging this fine piece of equipment that you've bought for yourself. :)