1.) I Believe the reason for these guys having multiple cards is due to the level of the areas the cards belong to they have tried to balance it so to get the card for the area of your level you have to kill someone your level.
Perhaps for helping people find them clues can be given be certain "spy" npcs when you talk to them they say stuff like "Hey have you noticed the furies have been visiting Sai kung a lot recently?" and posibly even hint as to where the nodes are.
2.) I dont think they can make an NPC that initiates a conversation with you so there would need to be a clear hint that you need to talk to them.
3.) Not sure how feasable this is. but it sounds like a good idea to me. although i think it would do better as an awakened ability possibly part of the Data mining branch
I think it would be cool if there was a way to use a device that whispers to you the direction of the nearest node eg.
nodetracker whispers>Weak Signal detected to the Southeast
Weak Signal more than 500mtrs
Signal 200-500mtrs
Strong Signal less than 200mtrs
But i would imagine that to be far to complicated to set up