There are really four tech trees. Each race gets one unique tree, and there's a special one I can't say much about at this point.

The research trees are much larger than most RTS games

There are also a number of other units that can be acquired that aren't part of the core faction set

We're big fans of a small number of unit types, where each unit has a specific role or roles at various stages of the game and won't go obsolete.

we also allow players to customize the names of their most powerful ships for immersive purposes

it leaves us with a number of challenges, not the least of which is that units can be so far away that their 3D mesh can't be represented by a single pixel. In Sins, when units first reach this point, they're replaced by icons appropriate for their distance, unit type, orientation, and ownership. As you continue to zoom out even farther, even the first-level icons become a problem, as they'll tend to cluster. At key thresholds, the icons themselves are replaced by even more simplified representations that contain the appropriate information and organization scheme for that level of zoom.

commodities market

My favorite is when the A.I. predicts that an enemy is going to be attacking you soon; this will trigger the playing of a tension-building "trouble is coming" piece.

A fourth tech tree, another race maybe?

one thing we havent heard anything about is "Fog of war".

my question is how far does it extend?
I dont want fog of war to apply within 100 yards of my ships, if you get my meaning. but I dont nescessarily want to see out into far orbit.
and how will this apply in/between solar systems?

If you're in a planet's gravity well, you can see everything in it. Otherwise you can't.