“EDGE capable TRX” means that this TRX has a functional unit which is 8-PSK modulator/demodulator.
Because of the constant symbol rate in the radio path the difference between the MCSs is a different proportion between the useful data and the noise protection bits.
It’s more software than hardware.
In fact the high MCS depends on max MCS allowed ( parameter ), radio conditions ( C/I ) and Abis resources ( additional TSs )…
So it’s logical that the TRAGE could give you better C/I when transmitting DL TBF than the TRAG could.
But it’s wrong to say that this will give you a higher MCS automaticly.
The abreviation means the max power of the hardware unit for the different modulations.
Yes, you can use all CS and MCS ( if it’s possible – permission, C/I, Abis ).