You should normally run a little toe-in on the front wheels, or run them dead ahead. More front toe-in reduces steering but increases stability.
The 2 degree rear block will give a little less rear grip, which may help on your tight track.
Foam tyres are usually black
Camber should be set for even tyre wear across the foam - normally 1 to 2 degrees negative would be about right. If you need to run a lot more than that, it may indicate that your suspension is too soft.
Spring and oil - for a low grip environment, something like Yokomo yellows all round, with 35wt oil should be a decent starting point. Maybe run a Green spring on the front, with 40wt oil. I've found that if you run the car on a softer spring than a yellow that starts to feel a bit vague, but really it is up to your own feel for the car at the end of the day. I would disconnect the anti-roll bars when the grip is low too.
Personally, I've always struggled with the Yoke around very tight tracks if the grip is down, it doesn't have a lot of steering by nature, it's generally stable.