ok, to begin with, u can't really improve distance on a paintball gun. Really, the main factor that affects distance is the fps ur shooting. The higher ur fps, the farther u will shoot. For accuracy, you could get a Palmers Stabalizer Regulator (if your using co2) which will improve ur consistency, making ur gun more accurate. These can be bought at www.g3pb.com
Also, you could get a new barrel like Custom Products, Dye, or Smart Parts barrel that would also improve ur accuracy. you can get barrels at www.paintballgear.com www.888paintball.com
which all have good selection. The best all around barrel length is 12 inches, and that is what u'll want.
The main thing that affects accuracy, is your paint to barrel match. If the paint ur using is too small for the barrel, the paint will bounce around in the barrel and cause really crappy accuracy. If it is too big, u will have more ball breaks. Also, make sure your paint is in good condition. When u buy ur paint, take a look at it to make sure it doesn't have any broken balls in the bag and it isn't dimpled or flattend at all. When your storing paint for a long time, rotate the bag of paint (or box) so one side of the paintballs don't get crushed. Things like this (that don't lose ur money) really really help your accuracy.
You can also switch to nitrogen, which improves ur accuracy since it doesnt have to change from a liquid to the gas, and is much more stable and consistent. If you switch to nitrogen, and u want to buy a new inline regulator, buy something like an Air America Vigilante or an AKA Sidewinder instead.
Don't put too much money into ur spyder... it would be better used to buy paint or buy a whole new gun like an Impulse, Bushmaster, or Autococker, or even something better.