Hello, I am flying from the U.S. to Mumbai. My flight goes from the U.S. to Brussels, then to Warsaw, and finally to Mumbai.
single ticket.

I assume I will have to go through or pass through the Schengen or security after landing in Brussels from the U.S for connection to Warsaw,

and will need to do same at warsaw?

also is there any fast pass for immigration/border control/security on connections for business class passengers?