Yes it is 55 plus and also worth getting the barov quest back at chillwind camp too, the only issue with the chillwind camp quest is that if your higher toons have done the quest to go to the horde place then they will be phased for the part where you are sent to kill the last Barov.
The cool part of the quest chain outside Scholo is that you can complete multiple parts of it with one run, just hand in the sections as you get them and go back into the instance to do the next part, no need for a multiple clear. I always do my last runs up to 60 in schol and the only thing you might need to worry about is dinging 60 on all your toons, my strategy always is to have one toon at 59 and the RAF toon hit 60, then grant a level to the 59 and you are pretty much 61 in a few minutes.