It usually does involve strapping as rugby players do seem to love taping every part of their bodies up. So it would be advised to learn ankles, knees, wrist, hands and shoulders or at least refresh them.
In terms of pre-game treatment they usually come to you with small problems that trigger point therapy works well. I would say that if you have a massage qualification use it as players do get grumpy if you dont give them a quick rub as well (they are a sensitive bunch).
In terms of on field treatment I would agree with Phyiso bob and say try adn work out a on pitch protocol for assessing each player.
You will find that it is just nerves as well as you will know more than the players anyway some do know a little bit but you shouldnt worry its always a learning experience, they will know it adn you will know it.
In terms of prices it all depends how high in the league's the club is and how far you have to travel most clubs where I live charge around £50- £75 per week this is for national midlands 3 in england but if you can get more go for it.
Hope this helps. If you have any further questions feel free to ask