Probably start here and read all the articles.
1: If you are talking about things like “ISO-14443”, and “ISO-15693”, those are standards published by the International Organization for Standards that define how the different types of RFID/NFC are to work.
2: Differences:
3: For culture, try the RFID Implantee FB group
4: You will need to understand basic electronics. Understanding how to use an Arduino board and a PN532 Shield from Adafruit would probably be a basic setup to start controlling things with NFC. If you have an xEM, Sparkfun has a 125khz RFID starter kit that I’ve used. If you want something already built, DT has the xEM access controller. https://dangerousthings.com/shop/xem-access-controller/
5: It can be daunting, but do your research and you’ll be fine.
I would say a LOT of posts on this forum are by newbies so you aren’t alone.