Ah...
Well if you haven't found it, you would be interested in the First Strike Single player minimod. There is a sticky for it in general discussion.
Install that, it will be installed as a seperate mod to regular FS, so you will have to start FSSP to play single player, it doesn't add SP to the main mod yet. Then you can play SP on many of the First Strike maps, and if I'm not mistaken all of the 2142 maps, northern strike included, with FS asssets and soldiers, even a few custom textures.
This map unfortunately does not have SP support yet. I still highly reccomend getting the FS SP minimod though, there is an update coming out for it soon to add in a few more maps and extend the AI support of Mos Espa.
I don't know the site, but there is a battlefield single player website for all your BF2142 and BF2 single player needs. Just google it, most the resources will be in their forums in stickies and such.
The only way to check what mods you have installed would be to open the game and go to the community tab, custom games, that will give you a list. For maps, you have to go to: C:/program files/electronic arts/2142/mods/MOD NAME[or 2142]/ levels
each folder in there is the name of a map you have for that mod, but all mods will have different maps.
hope that helps.
"Munchkin: One who, on being told that this is a game about politics and intrigue in 17th century Italy, asks to play a ninja."—
Andrew Rilstone