Since you’re new and full of doubts and intending to buy a lithium-ion fashlight, it’s imperative that you read this.
The charger works like this: set the battery in the charger cradle then connect it with a micro-USB cable just like you would recharge your phone. When the LED is green, it’s fully charged and you can put it back in.
I don’t think it will, at least not for long. Your torch is a light source, not a proper weapon. Better find other means of protection.
Now, welcome to BLF! ^:-) And yes, the TN12 is a good torch, in fact the 2014 edition was my first 18650 torch. I know better alternatives for my uses now (Convoy with Biscotti), but it’s still got a nice spot in my collection as my only forward clicky with dual switch.