I dunno whatcha mean by "how to use", you aim, you shoot, doesn't get any easier than that.
As for tunes and everything else....
1. Same story with most other weapon, GRapidB till you are happy with its speed/accuracy, then GForceB it. 2x/3x HShooter works as well, just expensive. Standard Air shit, it's a good weapon for pretty much any situation as it stuns like a motherfucker and hits like a truck, with HShooter setup you can even snipe and Hit 'n Run with it, Pacifar and Raystag are by far the best wielder of it, Izuna and Frau are okay if you are into your moebitches, but you won't have enough cap to bring them bitches' stats up.
2. Mod is kinda bad simply because of the lack of ammo. Force/GForceA + HShooter(or Shooter + Shooter for 3s) would be my honest personal recommendation. Any high capa M/L Arts are good for it, Victorl is probably the best wielder, Hoverion works as a cheap alternative. Play it like a Bazooka, try stay on higher ground, faceroll Air or anything else that presents his/her behinds at you.
3. Bad weapon, ask it to go home and be a family man.
As for sword, it will take you half a minute to figure it out by testing in training room.
