Graph Editor Help?

Hi Unity Community! I've been looking to create a node based graph editor for my team, however I find it kinda more difficult than some people say it is, lol. I'm not completely ignorant to the subject, just not sure exactly how to approach this. I know how to do basic editor scripting, editor windows, buttons, inspector overrides, event class, etc. ,however there are somethings I need advice on how creating a node based editor, specific things like:
.Creating an unique node in the editor window for each specific empty gameObject, (including when the gameObject is destroyed, so is its corresponding node)
.Mouse dragging a straight bezier line from one node to the other.
.When conditions are met in one node, the next node that's connected will activate
.Understanding / creating a node class(what it is and how to reference it)
.Open saved node editing project from empty gameObject(I think it's called serialization)

Basically, I'm trying to go for something like this:

There's not that much resources on this topic, so if anyone can give me any help on how to go about doing this, that would be great!

 

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Have you seen this?
http://forum.unity3d.com/threads/simple-node-editor.189230/

 

Yup, like a hundred times. While I do know some of the basics of creating the nodes like in your link, I need help with adding functionality to them, along with other things that was stated in my OP.