The compound on a track like bury is probably the most important but there is so much grip that the softer tyres just fold over.
Save those pinks for when its REALLY really (really) wet, they will be good.
The best tyres around there would be probably yellow mini spikes (schuey), they have the right balance of softness and spikeyness.
Greens would wear too quickly and blues maybe too agressive on the grass and too loose on the concrete stuff. I think..
re cams:
Yea to be honest, the crop factor for what I do is more a benefit than a drawback as I'm usually at the long end of things. I just got the 10.5mm fisheye for my d70 for super wide angles as there is no proper fisheye for the 1.3 crop.
The 5D resolution might push the limits of the 35-350, but yes Ive used it and its about the best lens for RC action (outdoors) that there can be. The reach is good and the wide angle is really useful, the push-pull design makes it great to use.. best of all they are fairly (!) cheap since they have been superceeded by the 28-300 IS.
What do you do to have a nice camera at work ? We make computer games and still the work camera is some pikey old effort.
