Your ideas for pre-race photos and starting line photos are good.
For the rest of it, remember that the difference between an average photo of someone just running, and a great photo of a runner often depends on something else in the picture, like breaking the tape in the case of the winner, or for most everybody else, the background. Careless photographers have terrible pictures with telephone poles sticking out of people's heads, crooked buildings, cut-off arms or legs, etc. But a sports photographer worth his salt will always think about these things in a running photo, especially the background which may include other runners as well as whatever else is in the field of view. (Unfortunately, except for steeplechase, there's not usually something there that you'd want to put in the foreground of a running picture besides the finish line.)
For race photos like the one you are describing, I would scout out the running trail to find a spot with a good background as it would be seen through the 200mm lens when facing the runners. If you carefully pick the spot you can get a beautiful background, like a patch of trees or some water (or snow-covered hillside as the case may be), even in the middle of a mostly ugly/drab environment. Take pictures of as many people as possible as they pass by that point in the race, while still leaving you a chance to move to the finish line and take pictures of the winners.
If you want more race-like photos, you might have to pick a spot within a mile from the start. You could get pictures with strong leaders and and closely-following packs of runners. This will also help you have time to get a picture of almost everyone and still have time to get to the finish line, but there is the risk that someone will be right behind someone else and you can't get their photo.
If you want mostly individual pictures and want to minimize the chance someone is blocked by other runners, then pick a spot farther from the start when runners will be much more separated. The cost of this is much less dramatic photos, more like an isolated person going for a jog. But at least the background will be nice if you choose your spot well.