Sound slike you have the scene well scoped out - I hear you about the close quarter, but if he's coming round the turn I'd be tempted to get a few in close with the 70-200 for the intensity and subject isolation.
Otherwise... I'd personally go something like
1- max of 3200 - keep noise down and at 3200 ISO you should still be able to get the shutter speed up, my fav trick is to underexpose if I'm eeking extra shutter speed and then lift a little in post.
2- 3D is risky I'd go 11 point single or dynamic - I'd use AF-C not manual and for sure if after the first lap I wasn't getting a good lock, maybe try and stop the aperture down a bit. But if the light is good you may be better off with higher shutter to freeze action rather than more DOF - just watch on the night and adapt.
3- With AF-C yes
4- You're call I rarely deviate from matirx
5- If you're on a monopod with a decent shutter speed I might be tempted to turn VR off. It does slow things a little and I'm always suspicious VR can't keep up in CH bursts (especially with an older lens). I feel I've blown shots with VR on.
Any practice you can get in advance would help and even on the night shooting earlier races. Sounds like a fun shoot - enjoy