I know very well CX77304.
According to Skyworks datasheet this PA have a second harmonic level of –7dBm @ full power in GSM900 (even more for DCS1800).
I can say that I measured, in average, –9dBm 2nd harmonic for this PA.
From a system point of view to meet the GSM spec for harmonics (–30dBm @ antenna connector), this PA requires at a LPF (~15dB rejection) and a diplexer, if is a dual-band design (~15dB rejection). You need some margin also.
The LPF and the Diplexer could be in any format (coupler+LPF, switchplexer, etc)
This PA have internal 50 ohms output match and do not require an external match.