Hi
the PMR radios here and across the pond are different so some of what i know may not be relevant.
range and clarity are what you need. here in the UK the radio is limited to 500mW output so keeping the antenna vertical and as high as possible help greatly, this means mounting it to the bike or top pocket ( I don't like things in pockets so mine are mounted to the bikes.)
you can get PTT (push to talk) headsets for most types of radio. they connect to the radio and have a speaker and mike that is fitted in the helmet. these are cheap and OK for a group ride when you need to talk at gas stops and such but are useless at anything over 40-50mph
for higher speed or communicating when on a long tour you need to have some sort of amp in the circuit.
this is what I use
i have a starcom1 intercom that is connected to my GPS and MP3 and a Cobra MT700 with PTT and bike power mod
the Cobra is a cheep radio but not dirt cheep it has useful features such as roger bleep and scan mode
powering the radio from the bike will give you extra range as the voltage drop from the batteries is used to limit the output power. having a cheaper radio also means that if it damaged by a spill or rain or stolen then you have not lost much. I am happy to stop for coffee without to much paranoia
also when traveling in a group the group communication is limited by the lowest power unit. having a high quality radio and amp set up only means that they can hear you OK and you only hear squawks and wind noise amplified!!
talk to all members of your group and find out how much they want to spend. take time to set up the systems and make sure mikes and speakers are placed correctly and don't cause discomfort. also practice using the systems as often as possible.
starcom info
try googleing 'cobra mt700' and see what comes up
