Newbie question regarding demo/audiorx.cpp

-----------------begin snipped-----------------------------
unsigned char buffer[PACKET_SIZE];

TimerPort::setTimer(PERIOD);

setCancel(THREAD_CANCEL_IMMEDIATE);

for( int i=0 ; true ; i++ ){
	int count;			
	do{
		const RTPData &d = socket->getCookedPacket();
		count = d.getSize();
	}while (count <= 0);

	if(i==0)
		ccxx_sleep(20);
			
	write(audiooutput,buffer,count);
----------------end snipped----------------------------------

Q0.) PACKET_SIZE seems to be calcaulated as: 
PACKET_SIZE=SAMPLING_RATE*PERIOD/1000
with SAMPLIN_RATE=8000 and PERIOD=20

so in this case the buffer will be 160 uchars.
Does RTPData.getSize () NEVER exceed this value?

Q1.) the buffer is written to the audio-ouput but the buffer is never filled with the recieved "audiobytes". Is this correct?

Q2.) Are there more "sources" besides the rfc to consult for better understanding of the rtp-lib?
I already found the reference and programmers manual.

Thanks
Arjan