i don't know the story lines of the games and there were also few or meybe just one game before the langrisser series but that game was bad so counting only the main games i will say it goes something like this:
i heard that langrisser5 takes place during and after langrisser4 i hope i could help you but please remember that all this is from what i read and heard and my own conclusions
Well I've played fully through at least one version of each of Langrisser games except for Langrisser 3. I've played part way through almost all of them except for the PC ports which I don't have anymore. The storylines are all pretty good with maybe the exception of the first Langrisser.
Well I don't have time to deeply cover te story alone but it's revolves around the Langrisser and Alhazard sword which kind fo represents good and evil. Basically most of the games your going against the a Empire or Emperor who is tring to take over the world. Your also at the same time going against Boser the Pricne of Darkness who is tring to have the demons and monsters rule the world. Also in certain Langrisser games their are different routes so if you want to you help the Empire rule the world or Help Boser take over the world you can do that as well.
A small part of the game does revolve around the friendship that are formed in the game and also some friends turn onmyou later as well as enemies that become your allies later as well. As for love their really isn't a lot of it in the game. In LAngrisser 3-5 the hero gets to chose a girl depedneing on how he answers certain questions through out the game. Towards the end of the game you get a chance to see if the girl will aceept you or not and the ending can change a little depending on if she accepts you or not.
Langrisser 3 gameplay is quite different. It's somewhat like large scale Dragon Force battles or at least the closest thing I can relate it to. It takes a while to get used to. Personally I would bother with Langrisser 3 unless your a die hard fan like me.
I think their like 22 total tracks for Langrisser 3 so I would guess about maybe 20 audio tracks but I can't check at the moment.
Langrisser 1, 2, 3 are the PC Langrisser games. I think Langirsser 1 and 2 are Japanese version and Langirsser 3 is Chinese. The Main Character in Langirsser 3 is Dyharte and he's blond. If your thinking of a Red haired guy your mostly thining of Sigma who was the main character in Langirsser 5 or Elwin who was the main character in Langirsser 2/Der Langrisser, or Ledin who is the main character in Langrisser 1.