I find myself constantly wishing I had some idea what the research tree looked like. For example, if I want to unlock plasma weapons, do I have to go down the laser weapon path first to unlock it, or am I going in completely in the wrong direction?If I want to get a satellite nexus, what do I need for it? How do I get this stealth armor I've heard about?

I have so many questions like this, and some sort of research tree with related manufacturing items would be of immense help.