I would like to find the angles of each of the diagonal members relative to the horizontal, this is so I can use method of joints/nodes to be able to calculate forces on the supporting structure. How should I do this?

There is a native component which calculates the angle between two vectors. You can input the lines as vectors, and as the second vector use for example unit x vector to refer to X-axis.

Iâ€™d go for something like this: first find a nice spot in your definition where data is very well sorted

for instance here you have all your stacks of points sorted as shown, each different branch is a â€śtowerâ€ť, and each sub-branch is a â€śZ-layerâ€ť of each tower, sorted bottom-up

this way it becomes easier to know which line is what, where it starts, where it ends
for instance, I want a diagonal line from previous level point 0 to next levelpoint 1:

That is amazing thank you, from the list panel is there a way of determining at which point they are at along the track? As in Iâ€™m not sure where {2;1} is as a location.