In case #1 I've never heard of a legal suit. Because of varying rules/organizations/etc, without a "race steward" its often pretty gray identifying who is at fault, so the determination of fault is your first problem. So insurance covers damage to your car and does not account for how that damage was accrued, who was at fault, etc. Even if both drivers had insurance, and it was agreed driver A was at fault, Driver A would have to agree to pay out of pocket to cover driver B's expenses... I've not heard of this happening, because you're on a race track after all.
"Give a man a match, and he'll be warm for a minute, but set him on fire, and he'll be warm for the rest of his life."