Compiler: c2000 SupportPackages in mathworks

   if (adcInitFlag == 0) {
       InitAdc();
       adcInitFlag = 1;
     }
   
     config_ADC_SOC0 ();
   
     /* Start for S-Function (c2802xadc): '<S3>/ADC1' incorporates:
      *  Outport: '<Root>/Out2'
      */
     if (adcInitFlag == 0) {
       InitAdc();
       adcInitFlag = 1;
     }

Notice the flag 'adcInitFlag' which is set to 1 after call to first InitAdc();.

The next condition for this call checks the flag against 'zero' which will not pass and hence second instance of InitAdc(); will not execute.
This Init is once required for the ADC module and is not block specific.

For the second question, we are not providing any input to ePWM block which can change in runtime, the code generation creates a _start function which is called from Init only.
However if user can provide some inputs to ePWM block like Timer Period value and provide sample time, the block will generate a function which is user defined and calls the same in step function.

for Example:

   /* Output and update for atomic system: '<Root>/InitPwm' */
      void InitPwm(void)
     {
       /* local block i/o variables */
       uint16_T rtb_DataTypeConversion;
     
       /* DataTypeConversion: <S2>/Data Type Conversion' incorporates:
        *  Constant: '<S2>/Constant1'
        *  Gain: '<S2>/PWM_Counter_Period'
      *  Sum: '<S2>/Add'
      */
     rtb_DataTypeConversion = (uint16_T)(__IQmpy(8L, ((int32_T)
       zhr486kgpfc0711_B.ui_Pfc_Adc_Va_ZYQ2 << 15U) + 32768L, 15) >> 2U);
   
     /* S-Function (c2802xpwm): '<S2>/ePWM' */
     {
       EPwm1Regs.TBPRD = (uint16_T)(rtb_DataTypeConversion);
     }
   }

HTH,