If you're going to be running the 100 and 200 in track, you're gonna want to hit plyometrics. I don't know about doing heavy weight, it's good to have that, it's also good to have that long distance endurance, but most of your training will be on the track.
Personally, i'm going to start working on this as well. I don't plan to focus solely on it though, i'm a cross trainer (going to get into triathlons), so I'm goign to work on speed, long distance, biking, swimming, weights, etc.
For speed, you're going to want to do sprints first off. Good measurements besides actually doing 100s and 200s are the 40m dash. It's also good to do long distance runs but make it a fartlek, dont' know what that is, look it up, there's 1000s of different fartleks people make up. It literally means speed play. But for speed, fartleks are the best for keeping your long distance endurance up while working on your speed. Also interval training. You can hit 50-400m intervals with some kind of set recovery distance (or time). Do like 8 intervals. And make sure you get lots of recovery time after your training. These are by no means daily routines. Interval training is a once or twice a week thing. You can hit fartleks in between, and make sure to do technique work. I'm not going to get into technique work since it's best learned through demonstration, you should know technique, look up drills for 'em.
When you hit the weight room, you can hit hard, but not if you're doing your interval training. In the gym just hit endurance workouts, low weight, but nail high reps, set recovery time, repeat. The routine you build will have to be your own and don't be afraid to take it easy, you need a lot of recovery time overall. It's easy as hell to overtrain in track and it's better to not train than to wear yourself down further.
As for plyometrics, i suggest looking up and reading up on 'em. There's all kinds. Hops, stair jumps, box jumps, short distance sprints, resistence sprints, clapping pushups, etc. These are very good things to get into your workouts, especially for warmups (along with a light jog). On the easier days, do fartleks and such, and have a good hard day where you do major intervals.
Personally i'd suggest cross training by throwing in a day in your week where you go out and jog 2-4 hours. Just to keep that long distance endurance up. My track coach challenged his team a couple years back to relay the Marathon. He ran the whole thing ... beat them! That's impressive, to not only be able to haul *** on short distances, but to be able to hold that for long distances as well. That's what i want to get, but not to that extreme! (i'm not a track runner! ..... yet! lol) but after I get this good combo (this year) I plan to hit training the bike and my swimming is okay, i'll realy work on that eventually, but bike would be the next, and i'll be set for triathlons. Eventually I'll get good enough for iron man triathlons and my dream is to hit an eco-challenge!
Anyway, just rambling. plyos, technique work, fartlek, and sprints are what you're going to want to look into. The weight room isn't neccesary for a track runner, but it's a great help. Don't expect to lift heavy though unless you want to go for that kind of cross training. If you can lift heavy (especially in the legs), then your speed work isn't good enough! lol Your plyos, intervals and speed work, throwing in some trails, hills, and stairs and resistance sprints should be all you need.