with regard to bluetooth i can recommend the Blue Ant Interphone - http://www.myblueant.com/interphone_helmet_kit.htm

i've recently started using one of these in competitive 4x4 events, we use them for almost constant conversation for a full day in an evironment where there is a lot of background noise - as driver i have a loud V8 engine and 3 separate cooling fans blaring away around me along with all the noises of a vehicle moving at speed over rough ground. the interphone is loud and clear enough that i can have a normal conversation with my co-driver who can be anything up to about 200ft away. a brilliant bit of kit.