Seeing as I'm not a whole lot older than you I can relate, but I know how to weightlift as I'm sure you do...
First off, you dont really have to do a lot of Sit-up/Ab-crunches to get a six pack. You just need to eat right and with some exercise, you will burn off the fat on your stomach. Throw that in with some Ab workout and you will have a great looking six-pack.
Second, there is a differnece in the way you lift in you want go get toned or just big. In order to get toned, do many reps/sets with a very small amount of weight will get your muscles toned. Doing heavy weight and few reps/sets will get you physically bigger. Depending on what position you play/if you plan on using creatine, I would suggest this road so your body is more physically ready to take the hits.
Last, if you want to increase/maintain your speed, you must lift using your legs. Dont only lift your upper body as you will gain weight that your legs must know carry. Balancing out upper and lower body will allow you to get faster. Make sure you strech as this will also help you get faster/more agile.
Sorry if you knew all of this already, just trying to help out a fellow Buckeye.