capacitor - Understanding LED driver circuit AC to DC conversion

I am recently working on mains socket outlet type LEDs lights. They all have very similar AC to DC conversion circuit.

^{simulate this circuit – Schematic created using CircuitLab}

1. 
   

   C1 is a X-2 type capacitor and I know it has Independence $$X_c= \frac{1}{2\pi fC} \approx 9.6 k\Omega$$ Thus, the AC current will be limited by this cap at 230/9.6k=23mA. But what the R1 does in the circuit?

   
   


2. 
   

   R2 is a big through hole resistor, does it act like a fuse or something?

   
   
   


3. 
   

   D1 is a Zener diode. I guess it is here to regulator the voltage to its breakdown voltage, like 5V or 12V. Am I right?

   
   


4. 
   

   This circuit doesn't have a transformer like 230V to 12v before the rectifier， would it be safe in practice?

   
   

Thanks a lot!