[quote=@Jeddaven]
Considering how advanced technology is at this point in time, are we also allowed the use of spacecraft -- and, if so, how far beyond the planet can we go?
[/quote]

You might want to read up on everything in the OP and look at a few NSs, that should help give you an idea of whats what. 

But yes, spacecraft are a serious asset as many, if not, all combatants wouldn't even be able to be here without space travel. That said, I have yet to see anyone go into any depth from the perspective of an orbital battle. So ask around once you get an NS up if your interested to see if anyone might be willing to add a space battle to the ever growing theaters of war. 

In terms of distance, we're trying to keep things focused on the planet itself, so, at most, probably some sort of engagement in high orbit to gain control over an area of the planet to provide orbital support. Currently, I like to imagine the space battles are a complete mess with deadly debris clouds drifting in crazy orbits around the planet while warships constantly fight for control over their respective nation's ground campaigns.