Well..i use the L/R and R outs from the PSR 740 for recording and they do not affect the recording level even if yu increase the internal monitor volume.I use sound forge and the only adjustmants I make are in the windows volume control.They do not change with any change in the internal volume at all...so what makes these two Extra outs on the 2000 special and how is it different from the Normal L/R and R outs.

The rca outs will work just like your old 740 did. They are a fixed volume.
The 1/4 inch jacks give you the option of connecting to an amp and still having the monitor speakers change volume with the knob. They give you a choice, that's all.