Awesome, you are going to love the ring. For me, it was a strong and immediate emotional response.
Everything that you said is spot on correct, and now things to work on/build upon. Firstly, the NFC Ring is just one component of an entire ecosystem.
Some others being: phone that can take full advantage of this emerging technology. Right now, that's going to be (mostly) an Android phone - and not all Android phones are the same (UX-wise). Some have insane NFC hardware (the Blackberry Priv is by far the best I've ever seen; with the Nexus lines - from 2013ish onward also being good/great) - not to say these are the only ones, I only can comment to those I've personally used.
Got the phone now what?
Probably not going to get a NFC door lock. Honestly, it is a lot of work still - and it requires the ability to drill into doors; not everyone is going to want to do this.
What about hacking? This is definitely a good and a couple of general ideas:
phone-related, you can setup up Smart Lock but also have the phone do additional work via Tasker/Trigger and scripting.
Hardware - if you like arduinos then there is KeyDuino. Though it is over, I'm fairly sure that you can still find these on ebay/forums/etc.
- Raspberry Pi (or other SBC) connected to a RC522. (Don't forget some female-female jumper wires) and there are a number of ways to use. Either via python or even Node.JS - depending on your goals.
As for someone skimming - I wouldn't worry about this too much. They would need to be right up on you (physically) and it is really then a question of what data you've put on your ring. If you are most concerned with a black hat cloning your ring to unlock your Android phone - solution: only authorize the 'inside' tag. But if you have your biz card on your ring (or Blockchain ID such as onename.com) - let them steal that.