A few questions

[Yef]

I got a few questions.

I built a System gravitational shield, and I can't open warp points to that system anymore. I thought it would the enemies the ones that wouldn't be able to do this.

Also, I was wondering about the function of the Tractor beam. Does it capture ships? Should I research it?

And finally, is it there any way to edit a saved game with the editor? (To add a moon to my homeworld )