More weight and less reps will make the muscle stronger and bigger. Less weight will make the muscle leaner and is basically meant to be used for cutting up/ reducing fat.
How old are you? I wouldn't bother going too hard on the weights, at least until your body has finished growing to its 'normal' capacity.
If you want to get fast, then it might be a good idea to mix the weight training with some sort of running system i.e. on the day you aren't training your legs at the gym, try doing some sprints e.g. maybe place cones 40m apart, sprint as fast as you can from one end to the other, then jog back, and repeat until you are ****ed.
For pure power (and this would probably help bursts of acceleration), find a short but steep hill or driveway or something similar, and run up it as fast as you can, jog back down, then repeat... again, until you are stuffed. It doesn't need to be a long hill, maybe 20 m would be enough. The point is to improve the power in your legs.
In both cases your legs will get one hell of a workout, especially in the hill run.
If you are looking for good abs, then there are a couple of things you can add to a normal ab routine (situps and leg raises etc.). Try doing situps holding a weight behind your head, maybe a 10kg plate or something. Abs are just like any other muscle, and you need weight to make them bigger. The other thing is to do something like skipping for 10 minutes (or at least build up to it eventually, start off with three sets of three minutes or something). A 10 minute skip session is equivalent to thirty minutes running, PLUS when you skip constant tension is kept on the muscles in the abs area for the duration you are doing it - you will have abs like a prize fighter in no time. Also improves the strength of your calves.
And obviously, cut out as much fat from the diet as possible. THe emphasis needs to be on increasing your metabolism if you want good abs, a person could do 1000 situps a day and still not have great abs if they aren't eating right and it is theri only form of exercise.
Hope this helps