(a) Yes, you are right to agree. In The Wagon Mound (No 2) the court found that, on the basis of these facts, the harm caused by spilling the fuel oil was reasonably foreseeable, even though it was something that was likely to happen only in rare cases.
Harm is reasonably foreseeable if there is a real and substantial risk that something like the event which happens might occur.
Harm is not reasonably foreseeable if the risk of it happening would be regarded as unreal either because the event would be considered physically impossible or because the possibility of it happening would have been regarded as so fantastic or far-fetched that no reasonable person would have paid any attention to it.
On the facts, the court held that the defendant would have realised there was a real risk of fire, and that the harm was therefore reasonably foreseeable.