What is the little oil lines purpose that is attached to the elbow that comes out of the case behind the cylinder? My 2000 doesn't have it but my 02 and 03's do. Is it a necessity on the newer bikes? Thanks.

 

If it's the one that runs back up into the top of the valve cover it's just another blowby hose. You can get a suitable replacement at any auto parts store.

 

this little oil line you speak of is a vent hose that allows the oil system to prime itself, the 2000 models must be primed using the bleed screw behind the oil filter, Bomb added this upgrade beginning with 2001 model years.
doesn't seem like a big deal really but in the event of a rollover if the 2000 model stays on its back for too long it can lose prime and not get it back, and if red light being on from lack of oil pressure is ignored you can smoke your crank bearings on the way back to the truck.