As far as I am aware, the Texas Jump gate was a sort of prototype I believe, the first generation of Jump Gates. The technology was new to humanity and it was still buggy. Whats worse, during the jump (I think) a Dark Matter cloud interdicted the 'transition' and caused a major feedback in the Jump Gate's power systems. This may have caused the Texas disaster. Also from what I remember, the disaster 'sucked' Dark Matter clouds into the system.
Now when it comes to the Jump Gates positions... Learning from mistakes, places them AWAY from major populated areas to avoid any disasters and peace of mind for the population, the Texas disaster still rings in the minds of the people.
Now for the 'creation' of the jump to another system, I have usually believed it was a gate 'encapsulating' a jump hole and stabilizing it. When a ships wants to 'jump' the gate sends energy into the hole, activating it safely. Then once its done, the gate 'saps' the energy from the hole, making it dormant, until the next ship.