Hi Toby,
You must be using an old version of the nodeditor so you need to use the clone node to get the 2 outputs.
There’s a new version of the nodeditor on forum would suggest you find that.
Unless you create the curves within the nodeditor you will need to run it every time.
If you create the curve points within the nodeditor they can be moved ( X & Y ) with nodes
thus the curvature comb will update as you modify them.
Hope that make sense.
Cheers
Barry