Opening a new command prompt window within a batch script

@REM Open a new window & display "Hello, world".
START cmd /k "echo Hello, world"

@REM Open a new window & execute multiple line of commands".
START cmd /k "echo Hello, world && echo How are you?"

@REM Open a new window and customize the pre-defined command line.
START cmd /k "prompt --=[$D $T]=--$_$L$P$G"