For the most part, all of the tips that you mention are good to start out with. Nothing beats practice! Get out and shoot someone running, even if it is your friend in your driveway. This question might help a bit as well: Taking sports and action shots with regular lenses
In my experience non-professional marathon photography is not that demanding on equipment. Usually lighting is fine since a standard 26.2 mile marathon typically occurs between 8am-12pm where I live, and usually during the seasons with more favorable weather. I mention this because your equipment for low light sports would be sub par, but for something like a marthon I don't think you will find it limiting at all. You may want to shoot with a shallow depth of field(small aperture, or small aperture plus a long focal length), to blur the background, but you still have some control over this and probably enough control over this with your current equipment.
Aperture priority is great if you specifically want to control the depth of field, or how much is in focus. f/8 might have been recommended to you because with that aperture, almost everything will be in focus in most situations. That doesn't mean that it is what you want to lock your camera into and leave it alone though. You might consider shutter priority mode so you can specifically control the amount of motion blur that the subject has. If you want a crisp clear runner, you will want a fast shutter speed. If you want to show motion blur of the runner moving, you will want a slow shutter speed. Using shutter priority mode will of course help you dial this in very easily to your liking.
Burst mode is typically a good idea with any sporting event, as the subject is moving and burst mode will help ensure that you do not miss the decisive or most important moment. In the case of a race, without burst mode you might get quite a few shots with other runners obstructing a view of a certain runner you would like to see in the frame. Burst mode can help with that. It also will help if you are trying to capture the moment when they cross the finish line for example.
One of the most important things to utilize when capturing moving subjects such as a runner, is to use AF-Continuous(Nikon), AI-Servo(Canon) or similar. This will constantly maintain focus on the subject(runner) as best as possible.
An important thing to remember at an event like this, is to move around and get as many perspectives as possible. No one wants to look at a shoot full of the same framing or background. Get elevated if possible, get on the course during a break in the action(a terrible idea generally speaking, but of course possible), move from the finish line to mile 15, etc.
If you are trying to shoot specific people like the elite runners, you will certainly want a long lens in the 70-200mm or longer range(as you have). Personally I shoot the runners as they are closer to me with a shorter lens, but that is just how I shoot. If I had to get coverage of an elite runner with varying backgrounds, I would want a long telephoto lens to do so.
I know you specifically are interested in settings and such, so here are a few examples from my experience:
Canon 17-55mm f/2.8 IS, at 17mm, f/5.6, 1/125sec, ISO 100:
Canon 17-55mm f/2.8 IS, at 17mm, f/7.1, 1/640sec, ISO 400, and yes I was a runner in the marathon :)
I tried to do a tracking shot here to show the movement, and also the emotion of the runner. Although it could have been done better by me. Canon 17-55mm f/2.8 IS, at 55mm, f/13, 1/50sec, ISO 400:
Canon 17-55mm f/2.8 IS, at 17mm, f/8, 1/800sec, ISO 400(these were my friends so I could get away with standing in front of them):