i cant comment on your exact situation but just as in surfing golf basketball ect. there are unspoken rules about being in a play park. the rules just as with individual foursomes in golf, court rules in basketball and lineups in surfing can change just a little bit with the crowd or spot. if you dont know the etiquette(sp) then it is your responsibility to ask. knowing boaters they tend to be a teaching and helpful group so feel free to approach and ask, most would be glad to explain and answer questions.
a couple of general hints....rescue your own gear as best as possible, a hand shake and thanks goes a long way in appreciation for those who help you out, take turns (alternate between eddies/certain playspots only have one good eddie and you must let the other side go if they are in a dangerous position), upstream has the formal right of way but they should look for an eddie or try to prevent pushing someone out of a feature, head nods go a long way as do verbal communication, time limits arent strict but you should be trying to do progressively harder tricks if your going to be in it for too long.
these are the ones that come to mind...oh and keep an eye on each others belongings....no need to let thieves prey.....