Sorry, I forgot you wrote assumption 'media correction is turned off" in GMAT doc.
The statement 1 and 2 are correct.
The statement 3 is correct for DSN Doppler for simulation. Because in simulation, w/o using ramp table, GMAT does not has any information about frequency band in order to get value from Table 13.1 Moyer's MathSpec. So GMAT takes the ratio from Transponder.TurnAroundRatio for calculation. Note that: User needs to specify ratio to an appropriated value as in Table 13.1.