Could Freespace 2 be moded to include 2 Nations At War (real player nations)
There already are, every time you play team multiplayer missions.
A Growth System (leveling)
It's called learning. You get better with the game when you fly a lot.
Just FRED them. Derelict had a mob of miners, for example... (although I am unsure whether I got your intent correctly or not)
and map jumps
Avery time you press Alt-J..
. The GTVA Command sends you the jump co-ordinates that they want you to go to.
If say someone had a server who could support this?
Well... Ignoring the problem of standalone servers not working at the moment (AFAIK), what you're essentially asking is converting FS2_Open engine into open universe form. The problem is, FS2_Open uses mission based gameplay, which means that it would be a massive task to re-design gameplay (and add a lot of new features) into the new form required by the open universe.
It would be far easier to port FreeSpace media into some existing moddable MMORPG, if there is such a thing, and modify it's gameplay to allow intra-system jumps and other FreeSpace features.
If it were possible, using the Infinity engine (no, not the Baldur's Gate one but this
) might be reasonably cool. Adjustments to flight mechanics would be needed to get it feel like FreeSpace, though...
Another possibility is the Total War approach. Make a separate simplified game engine, perhaps with 2D nodemap, perhaps in 3D, doesn't really matter. Hell, you could probably make a browser-based game if you're not picky about graphics...
This would take care of ship movements in general scale, resources, economy, leadership, systems management etc. Then, include a part in this engine that is essentially a FS2 mission generator that takes some variables like
-location (generates backgrounds based on system-specific instructions about the surroundings - number of suns, nebula or not, number and colour of nubula backgrounds, planet backgrounds)
-partaking forces (based on what's going on in the map, of course. Both Player-vs-Player and Player-vs-AI could probably be possible - with enough work on the code... which I likely can't possibly comprehend)
-mission goal(s) (destroy the enemy, capture certain enemy ship, defend installation/cap ship, or whatever is specified - how complex the goals could be would be dependant on the coder who would write the mission generation script)
...and build a FS2 mission file based on the information given from the general-view engine, and possibly some player feed for specific goal like capturing a destroyer and adding it to your own fleet or somesuch.
Then, when the mission was written, the "total-war-engine" would run FS2_Open, make you play the mission, then perhaps use a scripting hook to record the mission outcome and modify variables accordingly to represent the losses and victories.
Also, I could refer you to a project with some similarity to this, but without external "map", or somesuch: The Babylon Project's perhaps the most promising campaign-in-making, Babylonian History X, or BHX, which would effectively introduce dynamic (to certain extent) campaigns into FS2_Open engine (although only for TBP).
These are AFAIK the best options of introducing strategic elements into FS2_Open. Unless you can do it yourself, though, or find similarly minded people, FS2_Open will (with very high probability) not have this kind of things integrated to the engine. SCP team would likely not support that kind of change, so you'd be on your own with it then. But, as far as I know, if you can do it no one's there to stop you from grabbing the source and making the changes you speak of.