I'd really like to see some loops forming, giving us a second route into the rich pickings of the Spinward systems.
Yes, I've been actively looking for back-doors, but no luck so far. We have three more Grav-Survey vessels under construction, so when they come out we can ramp up the search effort by 50%.
I am assuming that as we stand to develop now we don't stand a chance if Charlie ends up hostile anyway. Therefore, I'd recommend to just go for it to try and build up our base a bit more before the almost inevitable encounter with a psychotic race. (more psychotic than our own compatriots that is)
Hard to say... if Charlie attacked Earth directly, I think we could give him a pretty hot reception, since the combat would take place within range of our Missile Bases, RADAR/Point Defense Bases, and Fighter Bases. A general fleet action fought far from Earth might be dicey, though.