Half Bridge Circuit Queries

[roxy1001]

I'm analyzing this Half bridge Buck regulator circuit..
I wonder why these components (encircled) are used ?

1- Shottkey diode
2- I guess thats ferrite core inductor forming choke Filter .. Correct me if I'm wrong
3- Common mode choke.. Why secondary of choke is connected to the ground ?

Please help me understand this, as I m new to power electronics.
Tell me if further reading required to understand concepts more clearly. I would appreciate if you provide relevant links
Thanks in advance !

 

[FvM]

1. The schottky diode isn't necessarily required in a synchronous buck converter.
2. It's the buck converter inductor, not a filter
3. The schematic is flawed, shorting the common mode choke. There must be different ground nets.