The barrel you have is a Tippmann Flatline barrel.  They aren't the most accure barrels, but are good for laying down surpressive fire.  The extra range it offers isn't always that great because the balls won't always break at the distances it can reach, caused by the loss of velocity over distance.  I personally prefer a normal, straight barrel.  The extra distance the Flatline offers doesn't fit my style of play and I need the extra accuracy a normal barrel offers.  Just play with it for a while, and if you find that you don't like it then get another.  Its as simple as that.

The trigger thing you're hearing about is the E-Grip/Trigger upgrade.  It would fit your 98.  However, the 3 round burst and full-auto modes are often not allowed at sanctioned fields.  So unless you're playing on private fields with your buddies only, you shouldn't get it for simply the extra modes it offers.  The lighter trigger pull is nice, though.  Both of these upgrades are viewable on the Tippmann website, so if you want to check them out, just go take a look.

Don't go dumping money into your 98.  Just save your money and go play with it.  As you play with it, you'll find things that you don't like or want to change about it, and from there you can upgrade accordingly.  Don't just go blindly spending money on it though.  Its not worth it, and if you find that you really like the game, then you'll most likely want to get a new marker, and you can spend the money instead on a new gun.