Well... I happen to own both FS and FS2.
From personal experience, it has little historty involved (unless it describes out-dated ships). But instead both FS and FS2 are an ongoing storyline.
Heck, the connection between FS/FS2 is perfect. FS takes place right before, and during the Great War. Silent Threat (the FS expansion pak) takes place near the end of the Great War. And FS2 is 30 years after the end of the war.... and those pesky Shivans are back for more.
The Freespace Trilogy is just one on-going story. As for history, there is some involved, including if not relative Tech Room. Actually, the Tech Room is where you can look up on what you want about what timeline you are trying to locate.
Not bad if you ask me, considering that Volition and Interplay were entering the 'new times' when the games were made.