How to choose Driver and Power amp in RF Transmitter part.

Hi,

Currently I am analyzing Tx part and given one Driver amp. and one two stage or three stage Power amp.
Can some one help to understand what is the difference to using of two stage or three stage PA except gain if it is possible to get power with 2 stage.

And for example given OP1dB =33 dBm and what will be Pavg in this case?

Only two watts output? You should only need a one stage power amplifier (driver + power amp).